64991020 has 24 divisors (see below), whose sum is σ = 143665200. Its totient is φ = 24628032.

The previous prime is 64990999. The next prime is 64991029. The reversal of 64991020 is 2019946.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (64991029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85135 + ... + 85894.

It is an arithmetic number, because the mean of its divisors is an integer number (5986050).

Almost surely, 2^64991020 is an apocalyptic number.

It is an amenable number.

64991020 is an abundant number, since it is smaller than the sum of its proper divisors (78674180).

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

64991020 is a wasteful number, since it uses less digits than its factorization.

64991020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171057 (or 171055 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 64991020 is about 8061.7008131039. The cubic root of 64991020 is about 402.0540590486.

The spelling of 64991020 in words is "sixty-four million, nine hundred ninety-one thousand, twenty".