21247136 has 12 divisors (see below), whose sum is σ = 41830362. Its totient is φ = 10623552.

The previous prime is 21247133. The next prime is 21247151. The reversal of 21247136 is 63174212.

It can be written as a sum of positive squares in only one way, i.e., 20757136 + 490000 = 4556^2 + 700^2 .

It is not an unprimeable number, because it can be changed into a prime (21247133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331955 + ... + 332018.

Almost surely, 2^21247136 is an apocalyptic number.

It is an amenable number.

21247136 is a deficient number, since it is larger than the sum of its proper divisors (20583226).

21247136 is an equidigital number, since it uses as much as digits as its factorization.

21247136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 663983 (or 663975 counting only the distinct ones).

The product of its digits is 2016, while the sum is 26.

The square root of 21247136 is about 4609.4615737633. The cubic root of 21247136 is about 276.9704686855.

The spelling of 21247136 in words is "twenty-one million, two hundred forty-seven thousand, one hundred thirty-six".