21731340 has 48 divisors (see below), whose sum is σ = 62270208. Its totient is φ = 5659584.

The previous prime is 21731317. The next prime is 21731363. The reversal of 21731340 is 4313712.

It is an interprime number because it is at equal distance from previous prime (21731317) and next prime (21731363).

It is a super-2 number, since 2×21731340² = 944502276391200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1632 + ... + 6791.

It is an arithmetic number, because the mean of its divisors is an integer number (1297296).

Almost surely, 2^21731340 is an apocalyptic number.

21731340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21731340 is an abundant number, since it is smaller than the sum of its proper divisors (40538868).

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

21731340 is a wasteful number, since it uses less digits than its factorization.

21731340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8478 (or 8476 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21731340 is about 4661.6885352842. The cubic root of 21731340 is about 279.0586585468.

The spelling of 21731340 in words is "twenty-one million, seven hundred thirty-one thousand, three hundred forty".