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1981897 = 3375881
BaseRepresentation
bin111100011110111001001
310201200122121
413203313021
51001410042
6110251241
722563061
oct7436711
93650577
101981897
111134035
127b6b21
13545128
143983a1
15292367
hex1e3dc9

1981897 has 4 divisors (see below), whose sum is σ = 1988116. Its totient is φ = 1975680.

The previous prime is 1981891. The next prime is 1981901. The reversal of 1981897 is 7981891.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1115136 + 866761 = 1056^2 + 931^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-1981897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2604 + ... + 3277.

It is an arithmetic number, because the mean of its divisors is an integer number (497029).

21981897 is an apocalyptic number.

1981897 is the 753-rd centered heptagonal number.

It is an amenable number.

1981897 is a deficient number, since it is larger than the sum of its proper divisors (6219).

1981897 is an equidigital number, since it uses as much as digits as its factorization.

1981897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6218.

The product of its digits is 36288, while the sum is 43.

The square root of 1981897 is about 1407.7986361692. The cubic root of 1981897 is about 125.6108130642.

The spelling of 1981897 in words is "one million, nine hundred eighty-one thousand, eight hundred ninety-seven".

Divisors: 1 337 5881 1981897