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1987381 = 111937257
BaseRepresentation
bin111100101001100110101
310201222011201
413211030311
51002044011
6110332501
722615054
oct7451465
93658151
101987381
111138170
127ba131
13547786
1439a39b
15293cc1
hex1e5335

1987381 has 16 divisors (see below), whose sum is σ = 2352960. Its totient is φ = 1658880.

The previous prime is 1987373. The next prime is 1987411. The reversal of 1987381 is 1837891.

1987381 = T131 + T132 + ... + T241.

It is a 6-Lehmer number, since φ(1987381) divides (1987381-1)6.

It is a cyclic number.

It is not a de Polignac number, because 1987381 - 23 = 1987373 is a prime.

It is a super-2 number, since 2×19873812 = 7899366478322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

1987381 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1987381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7605 + ... + 7861.

It is an arithmetic number, because the mean of its divisors is an integer number (147060).

21987381 is an apocalyptic number.

1987381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1987381 is a deficient number, since it is larger than the sum of its proper divisors (365579).

1987381 is a wasteful number, since it uses less digits than its factorization.

1987381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324.

The product of its digits is 12096, while the sum is 37.

The square root of 1987381 is about 1409.7450124047. The cubic root of 1987381 is about 125.7265633301.

The spelling of 1987381 in words is "one million, nine hundred eighty-seven thousand, three hundred eighty-one".

Divisors: 1 11 19 37 209 257 407 703 2827 4883 7733 9509 53713 104599 180671 1987381