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42000021 = 327666667
BaseRepresentation
bin1010000000110…
…1111010010101
32221000211012100
42200031322111
541223000041
64100112313
71016665020
oct240157225
987024170
1042000021
1121787268
1212095699
138916cab
1458141b7
153a496b6
hex280de95

42000021 has 12 divisors (see below), whose sum is σ = 69333472. Its totient is φ = 23999976.

The previous prime is 42000019. The next prime is 42000029. The reversal of 42000021 is 12000024.

It is not a de Polignac number, because 42000021 - 21 = 42000019 is a prime.

It is a super-3 number, since 3×420000213 (a number of 24 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 41999967 and 42000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42000029) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 333271 + ... + 333396.

Almost surely, 242000021 is an apocalyptic number.

It is an amenable number.

42000021 is a deficient number, since it is larger than the sum of its proper divisors (27333451).

42000021 is a wasteful number, since it uses less digits than its factorization.

42000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 666680 (or 666677 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 42000021 is about 6480.7423185928. The cubic root of 42000021 is about 347.6027224224.

Adding to 42000021 its reverse (12000024), we get a palindrome (54000045).

The spelling of 42000021 in words is "forty-two million, twenty-one", and thus it is an aban number and an uban number.

Divisors: 1 3 7 9 21 63 666667 2000001 4666669 6000003 14000007 42000021