21815492 has 6 divisors (see below), whose sum is σ = 38177118. Its totient is φ = 10907744.

The previous prime is 21815483. The next prime is 21815527. The reversal of 21815492 is 29451812.

It can be written as a sum of positive squares in only one way, i.e., 17422276 + 4393216 = 4174^2 + 2096^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2726933 + ... + 2726940.

It is an arithmetic number, because the mean of its divisors is an integer number (6362853).

Almost surely, 2^21815492 is an apocalyptic number.

It is an amenable number.

21815492 is a deficient number, since it is larger than the sum of its proper divisors (16361626).

21815492 is a wasteful number, since it uses less digits than its factorization.

21815492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5453877 (or 5453875 counting only the distinct ones).

The product of its digits is 5760, while the sum is 32.

The square root of 21815492 is about 4670.7057282599. The cubic root of 21815492 is about 279.4184016204.

The spelling of 21815492 in words is "twenty-one million, eight hundred fifteen thousand, four hundred ninety-two".