21693440 has 88 divisors (see below), whose sum is σ = 55023360. Its totient is φ = 8183808.

The previous prime is 21693437. The next prime is 21693493. The reversal of 21693440 is 4439612.

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, 97169 + ... + 97391.

Almost surely, 2^21693440 is an apocalyptic number.

21693440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21693440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27511680).

21693440 is an abundant number, since it is smaller than the sum of its proper divisors (33329920).

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

21693440 is a wasteful number, since it uses less digits than its factorization.

21693440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267 (or 249 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 21693440 is about 4657.6217107017. The cubic root of 21693440 is about 278.8963357206.

The spelling of 21693440 in words is "twenty-one million, six hundred ninety-three thousand, four hundred forty".