21171912 has 32 divisors (see below), whose sum is σ = 53071200. Its totient is φ = 7038464.

The previous prime is 21171911. The next prime is 21171929. The reversal of 21171912 is 21917112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21171911) 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, 10264 + ... + 12152.

It is an arithmetic number, because the mean of its divisors is an integer number (1658475).

Almost surely, 2^21171912 is an apocalyptic number.

It is an amenable number.

21171912 is an abundant number, since it is smaller than the sum of its proper divisors (31899288).

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

21171912 is a wasteful number, since it uses less digits than its factorization.

21171912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2365 (or 2361 counting only the distinct ones).

The product of its digits is 252, while the sum is 24.

The square root of 21171912 is about 4601.2946004358. The cubic root of 21171912 is about 276.6432173155.

The spelling of 21171912 in words is "twenty-one million, one hundred seventy-one thousand, nine hundred twelve".