21431656 has 16 divisors (see below), whose sum is σ = 40233600. Its totient is φ = 10702704.

The previous prime is 21431647. The next prime is 21431681. The reversal of 21431656 is 65613412.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11305 + ... + 13063.

It is an arithmetic number, because the mean of its divisors is an integer number (2514600).

Almost surely, 2^21431656 is an apocalyptic number.

It is an amenable number.

21431656 is a deficient number, since it is larger than the sum of its proper divisors (18801944).

21431656 is a wasteful number, since it uses less digits than its factorization.

21431656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3288 (or 3284 counting only the distinct ones).

The product of its digits is 4320, while the sum is 28.

The square root of 21431656 is about 4629.4336586671. The cubic root of 21431656 is about 277.7699388840.

The spelling of 21431656 in words is "twenty-one million, four hundred thirty-one thousand, six hundred fifty-six".