21695640 has 32 divisors (see below), whose sum is σ = 65087280. Its totient is φ = 5785472.

The previous prime is 21695627. The next prime is 21695669. The reversal of 21695640 is 4659612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 90279 + ... + 90518.

Almost surely, 2^21695640 is an apocalyptic number.

21695640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21695640 is an abundant number, since it is smaller than the sum of its proper divisors (43391640).

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

21695640 is a wasteful number, since it uses less digits than its factorization.

21695640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180811 (or 180807 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 21695640 is about 4657.8578767498. The cubic root of 21695640 is about 278.9057633202.

The spelling of 21695640 in words is "twenty-one million, six hundred ninety-five thousand, six hundred forty".