21279992 has 8 divisors (see below), whose sum is σ = 39900000. Its totient is φ = 10639992.

The previous prime is 21279959. The next prime is 21280001. The reversal of 21279992 is 29997212.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1329992 + ... + 1330007.

It is an arithmetic number, because the mean of its divisors is an integer number (4987500).

Almost surely, 2^21279992 is an apocalyptic number.

It is an amenable number.

21279992 is a deficient number, since it is larger than the sum of its proper divisors (18620008).

21279992 is a wasteful number, since it uses less digits than its factorization.

21279992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2660005 (or 2660001 counting only the distinct ones).

The product of its digits is 40824, while the sum is 41.

The square root of 21279992 is about 4613.0241707583. The cubic root of 21279992 is about 277.1131617212.

The spelling of 21279992 in words is "twenty-one million, two hundred seventy-nine thousand, nine hundred ninety-two".