21940724 has 24 divisors (see below), whose sum is σ = 42033768. Its totient is φ = 9959040.

The previous prime is 21940703. The next prime is 21940729. The reversal of 21940724 is 42704912.

It can be written as a sum of positive squares in 4 ways, for example, as 19600 + 21921124 = 140^2 + 4682^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21940729) 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, 287 + ... + 6630.

It is an arithmetic number, because the mean of its divisors is an integer number (1751407).

Almost surely, 2^21940724 is an apocalyptic number.

It is an amenable number.

21940724 is a deficient number, since it is larger than the sum of its proper divisors (20093044).

21940724 is a wasteful number, since it uses less digits than its factorization.

21940724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6995 (or 6993 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21940724 is about 4684.0926549333. The cubic root of 21940724 is about 279.9520496120.

The spelling of 21940724 in words is "twenty-one million, nine hundred forty thousand, seven hundred twenty-four".