21263908 has 6 divisors (see below), whose sum is σ = 37211846. Its totient is φ = 10631952.

The previous prime is 21263903. The next prime is 21263909. The reversal of 21263908 is 80936212.

It can be written as a sum of positive squares in only one way, i.e., 19079424 + 2184484 = 4368^2 + 1478^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21263908.

It is not an unprimeable number, because it can be changed into a prime (21263903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2657985 + ... + 2657992.

Almost surely, 2^21263908 is an apocalyptic number.

It is an amenable number.

21263908 is a deficient number, since it is larger than the sum of its proper divisors (15947938).

21263908 is a wasteful number, since it uses less digits than its factorization.

21263908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5315981 (or 5315979 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21263908 is about 4611.2805162991. The cubic root of 21263908 is about 277.0433275550.

The spelling of 21263908 in words is "twenty-one million, two hundred sixty-three thousand, nine hundred eight".