21457660 has 24 divisors (see below), whose sum is σ = 51498720. Its totient is φ = 7356864.

The previous prime is 21457649. The next prime is 21457679. The reversal of 21457660 is 6675412.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76495 + ... + 76774.

It is an arithmetic number, because the mean of its divisors is an integer number (2145780).

Almost surely, 2^21457660 is an apocalyptic number.

21457660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21457660 is an abundant number, since it is smaller than the sum of its proper divisors (30041060).

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

21457660 is a wasteful number, since it uses less digits than its factorization.

21457660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153285 (or 153283 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 21457660 is about 4632.2413581332. The cubic root of 21457660 is about 277.8822370980.

The spelling of 21457660 in words is "twenty-one million, four hundred fifty-seven thousand, six hundred sixty".