21047724 has 18 divisors (see below), whose sum is σ = 53204060. Its totient is φ = 7015896.

The previous prime is 21047713. The next prime is 21047771. The reversal of 21047724 is 42774012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (18).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 292294 + ... + 292365.

Almost surely, 2^21047724 is an apocalyptic number.

It is an amenable number.

21047724 is an abundant number, since it is smaller than the sum of its proper divisors (32156336).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21047724 is a wasteful number, since it uses less digits than its factorization.

21047724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 584669 (or 584664 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 27.

The square root of 21047724 is about 4587.7798552241. The cubic root of 21047724 is about 276.1012545942.

The spelling of 21047724 in words is "twenty-one million, forty-seven thousand, seven hundred twenty-four".