21992371 has 4 divisors (see below), whose sum is σ = 22010272. Its totient is φ = 21974472.

The previous prime is 21992357. The next prime is 21992401. The reversal of 21992371 is 17329912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21992371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21992351) 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, 6960 + ... + 9613.

It is an arithmetic number, because the mean of its divisors is an integer number (5502568).

Almost surely, 2^21992371 is an apocalyptic number.

21992371 is a deficient number, since it is larger than the sum of its proper divisors (17901).

21992371 is a wasteful number, since it uses less digits than its factorization.

21992371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17900.

The product of its digits is 6804, while the sum is 34.

The square root of 21992371 is about 4689.6024351751. The cubic root of 21992371 is about 280.1715402936.

The spelling of 21992371 in words is "twenty-one million, nine hundred ninety-two thousand, three hundred seventy-one".