64891620 has 36 divisors (see below), whose sum is σ = 196838460. Its totient is φ = 17304384.

The previous prime is 64891609. The next prime is 64891621. The reversal of 64891620 is 2619846.

64891620 is a `hidden beast` number, since 648 + 9 + 1 + 6 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 14424804 + 50466816 = 3798^2 + 7104^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (64891621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 180075 + ... + 180434.

It is an arithmetic number, because the mean of its divisors is an integer number (5467735).

Almost surely, 2^64891620 is an apocalyptic number.

64891620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

64891620 is an abundant number, since it is smaller than the sum of its proper divisors (131946840).

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

64891620 is a wasteful number, since it uses less digits than its factorization.

64891620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360524 (or 360519 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 64891620 is about 8055.5335018855. The cubic root of 64891620 is about 401.8489816646.

The spelling of 64891620 in words is "sixty-four million, eight hundred ninety-one thousand, six hundred twenty".