21506764 has 24 divisors (see below), whose sum is σ = 38601360. Its totient is φ = 10480704.

The previous prime is 21506753. The next prime is 21506843. The reversal of 21506764 is 46760512.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48327 + ... + 48769.

It is an arithmetic number, because the mean of its divisors is an integer number (1608390).

Almost surely, 2^21506764 is an apocalyptic number.

It is an amenable number.

21506764 is a deficient number, since it is larger than the sum of its proper divisors (17094596).

21506764 is a wasteful number, since it uses less digits than its factorization.

21506764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729 (or 727 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 21506764 is about 4637.5385712682. The cubic root of 21506764 is about 278.0940454377.

The spelling of 21506764 in words is "twenty-one million, five hundred six thousand, seven hundred sixty-four".