21730956 has 24 divisors (see below), whose sum is σ = 54606384. Its totient is φ = 6686400.

The previous prime is 21730903. The next prime is 21730957. The reversal of 21730956 is 65903712.

It is not an unprimeable number, because it can be changed into a prime (21730957) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69495 + ... + 69806.

It is an arithmetic number, because the mean of its divisors is an integer number (2275266).

Almost surely, 2^21730956 is an apocalyptic number.

21730956 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21730956 is an abundant number, since it is smaller than the sum of its proper divisors (32875428).

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

21730956 is a wasteful number, since it uses less digits than its factorization.

21730956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139321 (or 139319 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 33.

The square root of 21730956 is about 4661.6473483094. The cubic root of 21730956 is about 279.0570148507.

The spelling of 21730956 in words is "twenty-one million, seven hundred thirty thousand, nine hundred fifty-six".