21047912 has 8 divisors (see below), whose sum is σ = 39464850. Its totient is φ = 10523952.

The previous prime is 21047911. The next prime is 21047927. The reversal of 21047912 is 21974012.

It can be written as a sum of positive squares in only one way, i.e., 17023876 + 4024036 = 4126^2 + 2006^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21047911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1315487 + ... + 1315502.

Almost surely, 2^21047912 is an apocalyptic number.

It is an amenable number.

21047912 is a deficient number, since it is larger than the sum of its proper divisors (18416938).

21047912 is a wasteful number, since it uses less digits than its factorization.

21047912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2630995 (or 2630991 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21047912 is about 4587.8003443916. The cubic root of 21047912 is about 276.1020766448.

The spelling of 21047912 in words is "twenty-one million, forty-seven thousand, nine hundred twelve".