21207748 has 24 divisors (see below), whose sum is σ = 39372480. Its totient is φ = 9973920.

The previous prime is 21207733. The next prime is 21207749. The reversal of 21207748 is 84770212.

It is not an unprimeable number, because it can be changed into a prime (21207749) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 3723 + ... + 7501.

It is an arithmetic number, because the mean of its divisors is an integer number (1640520).

Almost surely, 2^21207748 is an apocalyptic number.

It is an amenable number.

21207748 is a deficient number, since it is larger than the sum of its proper divisors (18164732).

21207748 is a wasteful number, since it uses less digits than its factorization.

21207748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3867 (or 3865 counting only the distinct ones).

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 21207748 is about 4605.1870754618. The cubic root of 21207748 is about 276.7992132747.

The spelling of 21207748 in words is "twenty-one million, two hundred seven thousand, seven hundred forty-eight".