21742956 has 36 divisors (see below), whose sum is σ = 56305704. Its totient is φ = 7070400.

The previous prime is 21742913. The next prime is 21742961. The reversal of 21742956 is 65924712.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21742956² = 945512271235872, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21742956.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 5890 + ... + 8841.

Almost surely, 2^21742956 is an apocalyptic number.

It is an amenable number.

21742956 is an abundant number, since it is smaller than the sum of its proper divisors (34562748).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21742956 is a wasteful number, since it uses less digits than its factorization.

21742956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14782 (or 14777 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21742956 is about 4662.9342693201. The cubic root of 21742956 is about 279.1083712043.

The spelling of 21742956 in words is "twenty-one million, seven hundred forty-two thousand, nine hundred fifty-six".