21657330 has 48 divisors (see below), whose sum is σ = 56556864. Its totient is φ = 5749920.

The previous prime is 21657289. The next prime is 21657331. The reversal of 21657330 is 3375612.

It is a happy number.

21657330 is a `hidden beast` number, since 2 + 1 + 657 + 3 + 3 + 0 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21657294 and 21657303.

It is not an unprimeable number, because it can be changed into a prime (21657331) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29427 + ... + 30153.

It is an arithmetic number, because the mean of its divisors is an integer number (1178268).

Almost surely, 2^21657330 is an apocalyptic number.

21657330 is an abundant number, since it is smaller than the sum of its proper divisors (34899534).

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

21657330 is a wasteful number, since it uses less digits than its factorization.

21657330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1071 (or 1068 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21657330 is about 4653.7436543067. The cubic root of 21657330 is about 278.7415033573.

The spelling of 21657330 in words is "twenty-one million, six hundred fifty-seven thousand, three hundred thirty".