21740440 has 32 divisors (see below), whose sum is σ = 49070160. Its totient is φ = 8668800.

The previous prime is 21740429. The next prime is 21740443. The reversal of 21740440 is 4404712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740443) 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, 16195 + ... + 17485.

Almost surely, 2^21740440 is an apocalyptic number.

21740440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21740440 is an abundant number, since it is smaller than the sum of its proper divisors (27329720).

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

21740440 is a wasteful number, since it uses less digits than its factorization.

21740440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1723 (or 1719 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21740440 is about 4662.6644743108. The cubic root of 21740440 is about 279.0976050547.

The spelling of 21740440 in words is "twenty-one million, seven hundred forty thousand, four hundred forty".