664166784 has 64 divisors (see below), whose sum is σ = 1769304240. Its totient is φ = 220747776.

The previous prime is 664166771. The next prime is 664166803. The reversal of 664166784 is 487661466.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×664166784² = 882235033937805312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140914 + ... + 145550.

Almost surely, 2^664166784 is an apocalyptic number.

664166784 is a gapful number since it is divisible by the number (64) 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 664166784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (884652120).

664166784 is an abundant number, since it is smaller than the sum of its proper divisors (1105137456).

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

664166784 is a wasteful number, since it uses less digits than its factorization.

664166784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027 (or 5015 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 48.

The square root of 664166784 is about 25771.4334874877. The cubic root of 664166784 is about 872.4871727137.

The spelling of 664166784 in words is "six hundred sixty-four million, one hundred sixty-six thousand, seven hundred eighty-four".