21999508 has 6 divisors (see below), whose sum is σ = 38499146. Its totient is φ = 10999752.

The previous prime is 21999469. The next prime is 21999539. The reversal of 21999508 is 80599912.

It can be written as a sum of positive squares in only one way, i.e., 12830724 + 9168784 = 3582^2 + 3028^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2749935 + ... + 2749942.

Almost surely, 2^21999508 is an apocalyptic number.

It is an amenable number.

21999508 is a deficient number, since it is larger than the sum of its proper divisors (16499638).

21999508 is a wasteful number, since it uses less digits than its factorization.

21999508 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5499881 (or 5499879 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 21999508 is about 4690.3633121540. The cubic root of 21999508 is about 280.2018442570.

The spelling of 21999508 in words is "twenty-one million, nine hundred ninety-nine thousand, five hundred eight".