21374640 has 120 divisors (see below), whose sum is σ = 82057248. Its totient is φ = 4884480.

The previous prime is 21374611. The next prime is 21374657. The reversal of 21374640 is 4647312.

21374640 is a `hidden beast` number, since 2 + 13 + 7 + 4 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2920 + ... + 7160.

Almost surely, 2^21374640 is an apocalyptic number.

21374640 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 21374640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41028624).

21374640 is an abundant number, since it is smaller than the sum of its proper divisors (60682608).

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

21374640 is a wasteful number, since it uses less digits than its factorization.

21374640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4267 (or 4258 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 21374640 is about 4623.2715689217. The cubic root of 21374640 is about 277.5233971020.

The spelling of 21374640 in words is "twenty-one million, three hundred seventy-four thousand, six hundred forty".