64978920 has 48 divisors (see below), whose sum is σ = 211182660. Its totient is φ = 17327616.

The previous prime is 64978909. The next prime is 64978931. The reversal of 64978920 is 2987946.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (64978909) and next prime (64978931).

It can be written as a sum of positive squares in 2 ways, for example, as 61496964 + 3481956 = 7842^2 + 1866^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 89889 + ... + 90608.

Almost surely, 2^64978920 is an apocalyptic number.

64978920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

64978920 is an abundant number, since it is smaller than the sum of its proper divisors (146203740).

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

64978920 is a wasteful number, since it uses less digits than its factorization.

64978920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180514 (or 180507 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 64978920 is about 8060.9503161848. The cubic root of 64978920 is about 402.0291060830.

The spelling of 64978920 in words is "sixty-four million, nine hundred seventy-eight thousand, nine hundred twenty".