21523556 has 12 divisors (see below), whose sum is σ = 38467968. Its totient is φ = 10532712.

The previous prime is 21523543. The next prime is 21523571. The reversal of 21523556 is 65532512.

It is a happy number.

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, 57056 + ... + 57431.

It is an arithmetic number, because the mean of its divisors is an integer number (3205664).

Almost surely, 2^21523556 is an apocalyptic number.

It is an amenable number.

21523556 is a deficient number, since it is larger than the sum of its proper divisors (16944412).

21523556 is a wasteful number, since it uses less digits than its factorization.

21523556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114538 (or 114536 counting only the distinct ones).

The product of its digits is 9000, while the sum is 29.

The square root of 21523556 is about 4639.3486611808. The cubic root of 21523556 is about 278.1664031448.

The spelling of 21523556 in words is "twenty-one million, five hundred twenty-three thousand, five hundred fifty-six".