64631994 has 64 divisors (see below), whose sum is σ = 157842432. Its totient is φ = 17222400.

The previous prime is 64631989. The next prime is 64631999. The reversal of 64631994 is 49913646.

It is an interprime number because it is at equal distance from previous prime (64631989) and next prime (64631999).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (64631999) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 93189 + ... + 93879.

It is an arithmetic number, because the mean of its divisors is an integer number (2466288).

Almost surely, 2^64631994 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 64631994, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78921216).

64631994 is an abundant number, since it is smaller than the sum of its proper divisors (93210438).

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

64631994 is a wasteful number, since it uses less digits than its factorization.

64631994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 851.

The product of its digits is 139968, while the sum is 42.

The square root of 64631994 is about 8039.4025897451. The cubic root of 64631994 is about 401.3123438421.

It can be divided in two parts, 646 and 31994, that added together give a triangular number (32640 = T₂₅₅).

The spelling of 64631994 in words is "sixty-four million, six hundred thirty-one thousand, nine hundred ninety-four".