21618748 has 6 divisors (see below), whose sum is σ = 37832816. Its totient is φ = 10809372.

The previous prime is 21618739. The next prime is 21618787. The reversal of 21618748 is 84781612.

It is a congruent number.

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, 2702340 + ... + 2702347.

Almost surely, 2^21618748 is an apocalyptic number.

It is an amenable number.

21618748 is a deficient number, since it is larger than the sum of its proper divisors (16214068).

21618748 is a wasteful number, since it uses less digits than its factorization.

21618748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5404691 (or 5404689 counting only the distinct ones).

The product of its digits is 21504, while the sum is 37.

The square root of 21618748 is about 4649.5965416367. The cubic root of 21618748 is about 278.5758812600.

It can be divided in two parts, 21618 and 748, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21618748 in words is "twenty-one million, six hundred eighteen thousand, seven hundred forty-eight".