21047930 has 16 divisors (see below), whose sum is σ = 37954440. Its totient is φ = 8404032.

The previous prime is 21047927. The next prime is 21047951. The reversal of 21047930 is 3974012.

It can be written as a sum of positive squares in 4 ways, for example, as 19386409 + 1661521 = 4403^2 + 1289^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21047930.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5216 + ... + 8324.

Almost surely, 2^21047930 is an apocalyptic number.

21047930 is a deficient number, since it is larger than the sum of its proper divisors (16906510).

21047930 is a wasteful number, since it uses less digits than its factorization.

21047930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3793.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21047930 is about 4587.8023061156. The cubic root of 21047930 is about 276.1021553515.

The spelling of 21047930 in words is "twenty-one million, forty-seven thousand, nine hundred thirty".