21207490 has 16 divisors (see below), whose sum is σ = 38229048. Its totient is φ = 8470656.

The previous prime is 21207469. The next prime is 21207493. The reversal of 21207490 is 9470212.

It can be written as a sum of positive squares in 4 ways, for example, as 20693401 + 514089 = 4549^2 + 717^2 .

It is not an unprimeable number, because it can be changed into a prime (21207493) by changing a digit.

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, 9304 + ... + 11356.

Almost surely, 2^21207490 is an apocalyptic number.

21207490 is a deficient number, since it is larger than the sum of its proper divisors (17021558).

21207490 is a wasteful number, since it uses less digits than its factorization.

21207490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3093.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21207490 is about 4605.1590634852. The cubic root of 21207490 is about 276.7980908157.

The spelling of 21207490 in words is "twenty-one million, two hundred seven thousand, four hundred ninety".