64997640 has 128 divisors (see below), whose sum is σ = 219628800. Its totient is φ = 17309376.

The previous prime is 64997633. The next prime is 64997687. The reversal of 64997640 is 4679946.

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 31 ways as a sum of consecutive naturals, for example, 87109 + ... + 87851.

It is an arithmetic number, because the mean of its divisors is an integer number (1715850).

Almost surely, 2^64997640 is an apocalyptic number.

64997640 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 64997640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109814400).

64997640 is an abundant number, since it is smaller than the sum of its proper divisors (154631160).

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

64997640 is an equidigital number, since it uses as much as digits as its factorization.

64997640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 775 (or 753 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 64997640 is about 8062.1113859832. Note that the first 3 decimals coincide. The cubic root of 64997640 is about 402.0677096909.

It can be divided in two parts, 649 and 97640, that added together give a palindrome (98289).

The spelling of 64997640 in words is "sixty-four million, nine hundred ninety-seven thousand, six hundred forty".