21171992 has 16 divisors (see below), whose sum is σ = 40770960. Its totient is φ = 10299744.

The previous prime is 21171991. The next prime is 21172003. The reversal of 21171992 is 29917112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35468 + ... + 36059.

It is an arithmetic number, because the mean of its divisors is an integer number (2548185).

Almost surely, 2^21171992 is an apocalyptic number.

It is an amenable number.

21171992 is a deficient number, since it is larger than the sum of its proper divisors (19598968).

21171992 is a wasteful number, since it uses less digits than its factorization.

21171992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71570 (or 71566 counting only the distinct ones).

The product of its digits is 2268, while the sum is 32.

The square root of 21171992 is about 4601.3032936332. The cubic root of 21171992 is about 276.6435657556.

The spelling of 21171992 in words is "twenty-one million, one hundred seventy-one thousand, nine hundred ninety-two".