64990720 has 80 divisors (see below), whose sum is σ = 159096960. Its totient is φ = 25452544.

The previous prime is 64990691. The next prime is 64990729. The reversal of 64990720 is 2709946.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×64990720² = 8447587372236800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 64990720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64990729) 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, 135441 + ... + 135919.

It is an arithmetic number, because the mean of its divisors is an integer number (1988712).

Almost surely, 2^64990720 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64990720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79548480).

64990720 is an abundant number, since it is smaller than the sum of its proper divisors (94106240).

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

64990720 is an equidigital number, since it uses as much as digits as its factorization.

64990720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555 (or 539 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 64990720 is about 8061.6822065869. The cubic root of 64990720 is about 402.0534404174.

The spelling of 64990720 in words is "sixty-four million, nine hundred ninety thousand, seven hundred twenty".