21279492 has 72 divisors (see below), whose sum is σ = 59393880. Its totient is φ = 6382080.

The previous prime is 21279469. The next prime is 21279493. The reversal of 21279492 is 29497212.

It can be written as a sum of positive squares in 4 ways, for example, as 3437316 + 17842176 = 1854^2 + 4224^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21279493) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18634 + ... + 19742.

It is an arithmetic number, because the mean of its divisors is an integer number (824915).

Almost surely, 2^21279492 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21279492, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29696940).

21279492 is an abundant number, since it is smaller than the sum of its proper divisors (38114388).

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

21279492 is a wasteful number, since it uses less digits than its factorization.

21279492 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1173 (or 1168 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21279492 is about 4612.9699760566. The cubic root of 21279492 is about 277.1109913309.

The spelling of 21279492 in words is "twenty-one million, two hundred seventy-nine thousand, four hundred ninety-two".