21402747 has 12 divisors (see below), whose sum is σ = 30958200. Its totient is φ = 14248608.

The previous prime is 21402739. The next prime is 21402763. The reversal of 21402747 is 74720412.

It is a happy number.

It is not a de Polignac number, because 21402747 - 2³ = 21402739 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21402747.

It is not an unprimeable number, because it can be changed into a prime (21402047) 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 11 ways as a sum of consecutive naturals, for example, 8308 + ... + 10574.

It is an arithmetic number, because the mean of its divisors is an integer number (2579850).

Almost surely, 2^21402747 is an apocalyptic number.

21402747 is a deficient number, since it is larger than the sum of its proper divisors (9555453).

21402747 is a wasteful number, since it uses less digits than its factorization.

21402747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3322 (or 3319 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 27.

The square root of 21402747 is about 4626.3103008769. The cubic root of 21402747 is about 277.6449887568.

The spelling of 21402747 in words is "twenty-one million, four hundred two thousand, seven hundred forty-seven".