21402536 has 8 divisors (see below), whose sum is σ = 40129770. Its totient is φ = 10701264.

The previous prime is 21402527. The next prime is 21402587. The reversal of 21402536 is 63520412.

It can be written as a sum of positive squares in only one way, i.e., 14485636 + 6916900 = 3806^2 + 2630^2 .

It is a tau number, because it is divible by the number of its divisors (8).

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 as a sum of consecutive naturals, namely, 1337651 + ... + 1337666.

Almost surely, 2^21402536 is an apocalyptic number.

It is an amenable number.

21402536 is a deficient number, since it is larger than the sum of its proper divisors (18727234).

21402536 is a wasteful number, since it uses less digits than its factorization.

21402536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2675323 (or 2675319 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21402536 is about 4626.2874964706. The cubic root of 21402536 is about 277.6440763617.

Adding to 21402536 its reverse (63520412), we get a palindrome (84922948).

The spelling of 21402536 in words is "twenty-one million, four hundred two thousand, five hundred thirty-six".