667421664 has 192 divisors, whose sum is σ = 2270338560. Its totient is φ = 166717440.

The previous prime is 667421641. The next prime is 667421681. The reversal of 667421664 is 466124766.

It is a happy number.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 163974 + ... + 167994.

It is an arithmetic number, because the mean of its divisors is an integer number (11824680).

Almost surely, 2^667421664 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 667421664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1135169280).

667421664 is an abundant number, since it is smaller than the sum of its proper divisors (1602916896).

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

667421664 is a wasteful number, since it uses less digits than its factorization.

667421664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4073 (or 4065 counting only the distinct ones).

The product of its digits is 290304, while the sum is 42.

The square root of 667421664 is about 25834.5052981473. The cubic root of 667421664 is about 873.9101157854.

The spelling of 667421664 in words is "six hundred sixty-seven million, four hundred twenty-one thousand, six hundred sixty-four".