21392090 has 16 divisors (see below), whose sum is σ = 39138120. Its totient is φ = 8416320.

The previous prime is 21392071. The next prime is 21392099. The reversal of 21392090 is 9029312.

It can be written as a sum of positive squares in 4 ways, for example, as 17732521 + 3659569 = 4211^2 + 1913^2 .

It is not an unprimeable number, because it can be changed into a prime (21392099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16925 + ... + 18144.

Almost surely, 2^21392090 is an apocalyptic number.

21392090 is a deficient number, since it is larger than the sum of its proper divisors (17746030).

21392090 is a wasteful number, since it uses less digits than its factorization.

21392090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35137.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 21392090 is about 4625.1583756667. The cubic root of 21392090 is about 277.5988988183.

The spelling of 21392090 in words is "twenty-one million, three hundred ninety-two thousand, ninety".