21036408 has 32 divisors (see below), whose sum is σ = 52823760. Its totient is φ = 6981120.

The previous prime is 21036371. The next prime is 21036409. The reversal of 21036408 is 80463012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21036409) 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, 3966 + ... + 7602.

Almost surely, 2^21036408 is an apocalyptic number.

It is an amenable number.

21036408 is an abundant number, since it is smaller than the sum of its proper divisors (31787352).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21036408 is a wasteful number, since it uses less digits than its factorization.

21036408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3887 (or 3883 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21036408 is about 4586.5464131523. The cubic root of 21036408 is about 276.0517651278.

The spelling of 21036408 in words is "twenty-one million, thirty-six thousand, four hundred eight".