21901756 has 12 divisors (see below), whose sum is σ = 40345480. Its totient is φ = 10374480.

The previous prime is 21901753. The next prime is 21901769. The reversal of 21901756 is 65710912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901751) 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, 144015 + ... + 144166.

Almost surely, 2^21901756 is an apocalyptic number.

It is an amenable number.

21901756 is a deficient number, since it is larger than the sum of its proper divisors (18443724).

21901756 is a wasteful number, since it uses less digits than its factorization.

21901756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288204 (or 288202 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21901756 is about 4679.9311960754. The cubic root of 21901756 is about 279.7862143629.

The spelling of 21901756 in words is "twenty-one million, nine hundred one thousand, seven hundred fifty-six".