21660402 has 16 divisors (see below), whose sum is σ = 43398432. Its totient is φ = 7207200.

The previous prime is 21660389. The next prime is 21660407. The reversal of 21660402 is 20406612.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21660407) 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, 777 + ... + 6627.

It is an arithmetic number, because the mean of its divisors is an integer number (2712402).

Almost surely, 2^21660402 is an apocalyptic number.

21660402 is an abundant number, since it is smaller than the sum of its proper divisors (21738030).

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

21660402 is a wasteful number, since it uses less digits than its factorization.

21660402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6473.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21660402 is about 4654.0736994594. The cubic root of 21660402 is about 278.7546821658.

The spelling of 21660402 in words is "twenty-one million, six hundred sixty thousand, four hundred two".