21508964 has 12 divisors (see below), whose sum is σ = 37716588. Its totient is φ = 10732800.

The previous prime is 21508957. The next prime is 21508973. The reversal of 21508964 is 46980512.

It can be written as a sum of positive squares in 2 ways, for example, as 9048064 + 12460900 = 3008^2 + 3530^2 .

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, 3077 + ... + 7244.

It is an arithmetic number, because the mean of its divisors is an integer number (3143049).

Almost surely, 2^21508964 is an apocalyptic number.

It is an amenable number.

21508964 is a deficient number, since it is larger than the sum of its proper divisors (16207624).

21508964 is a wasteful number, since it uses less digits than its factorization.

21508964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10846 (or 10844 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 21508964 is about 4637.7757599953. The cubic root of 21508964 is about 278.1035275095.

The spelling of 21508964 in words is "twenty-one million, five hundred eight thousand, nine hundred sixty-four".