21931368 has 32 divisors (see below), whose sum is σ = 55039200. Its totient is φ = 7282368.

The previous prime is 21931363. The next prime is 21931369. The reversal of 21931368 is 86313912.

It is not an unprimeable number, because it can be changed into a prime (21931361) 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, 5178 + ... + 8406.

It is an arithmetic number, because the mean of its divisors is an integer number (1719975).

Almost surely, 2^21931368 is an apocalyptic number.

It is an amenable number.

21931368 is an abundant number, since it is smaller than the sum of its proper divisors (33107832).

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

21931368 is a wasteful number, since it uses less digits than its factorization.

21931368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3521 (or 3517 counting only the distinct ones).

The product of its digits is 7776, while the sum is 33.

The square root of 21931368 is about 4683.0938491557. The cubic root of 21931368 is about 279.9122514151.

The spelling of 21931368 in words is "twenty-one million, nine hundred thirty-one thousand, three hundred sixty-eight".