21793490 has 24 divisors (see below), whose sum is σ = 41677092. Its totient is φ = 8203520.

The previous prime is 21793487. The next prime is 21793501. The reversal of 21793490 is 9439712.

It can be written as a sum of positive squares in 6 ways, for example, as 10975969 + 10817521 = 3313^2 + 3289^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21793490.

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 11 ways as a sum of consecutive naturals, for example, 881 + ... + 6660.

Almost surely, 2^21793490 is an apocalyptic number.

21793490 is a deficient number, since it is larger than the sum of its proper divisors (19883602).

21793490 is a wasteful number, since it uses less digits than its factorization.

21793490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7582 (or 7565 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 21793490 is about 4668.3498155130. The cubic root of 21793490 is about 279.3244342752.

The spelling of 21793490 in words is "twenty-one million, seven hundred ninety-three thousand, four hundred ninety".