21727440 has 200 divisors, whose sum is σ = 86423040. Its totient is φ = 4955904.

The previous prime is 21727429. The next prime is 21727451. The reversal of 21727440 is 4472712.

It is a happy number.

21727440 is a `hidden beast` number, since 217 + 2 + 7 + 440 = 666.

It is an interprime number because it is at equal distance from previous prime (21727429) and next prime (21727451).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 45121 + ... + 45599.

Almost surely, 2^21727440 is an apocalyptic number.

21727440 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 21727440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43211520).

21727440 is an abundant number, since it is smaller than the sum of its proper divisors (64695600).

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

21727440 is a wasteful number, since it uses less digits than its factorization.

21727440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511 (or 496 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 27.

The square root of 21727440 is about 4661.2702131501. The cubic root of 21727440 is about 279.0419638579.

The spelling of 21727440 in words is "twenty-one million, seven hundred twenty-seven thousand, four hundred forty".