21756916 has 24 divisors (see below), whose sum is σ = 39818240. Its totient is φ = 10389600.

The previous prime is 21756901. The next prime is 21756949. The reversal of 21756916 is 61965712.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8686 + ... + 10906.

Almost surely, 2^21756916 is an apocalyptic number.

It is an amenable number.

21756916 is a deficient number, since it is larger than the sum of its proper divisors (18061324).

21756916 is a wasteful number, since it uses less digits than its factorization.

21756916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2335 (or 2333 counting only the distinct ones).

The product of its digits is 22680, while the sum is 37.

The square root of 21756916 is about 4664.4309406400. The cubic root of 21756916 is about 279.1680919904.

The spelling of 21756916 in words is "twenty-one million, seven hundred fifty-six thousand, nine hundred sixteen".