64421640 has 96 divisors (see below), whose sum is σ = 210951000. Its totient is φ = 17049600.

The previous prime is 64421633. The next prime is 64421657. The reversal of 64421640 is 4612446.

64421640 is a `hidden beast` number, since 644 + 2 + 16 + 4 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 15729156 + 48692484 = 3966^2 + 6978^2 .

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, 53040 + ... + 54240.

Almost surely, 2^64421640 is an apocalyptic number.

64421640 is a gapful number since it is divisible by the number (60) 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 64421640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105475500).

64421640 is an abundant number, since it is smaller than the sum of its proper divisors (146529360).

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

64421640 is a wasteful number, since it uses less digits than its factorization.

64421640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1367 (or 1360 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 64421640 is about 8026.3092389965. The cubic root of 64421640 is about 400.8764946566.

The spelling of 64421640 in words is "sixty-four million, four hundred twenty-one thousand, six hundred forty".