667691640 has 768 divisors, whose sum is σ = 2994278400. Its totient is φ = 130636800.

The previous prime is 667691639. The next prime is 667691681. The reversal of 667691640 is 46196766.

It is a happy number.

667691640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×667691640² = 891624252251779200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 18045702 + ... + 18045738.

It is an arithmetic number, because the mean of its divisors is an integer number (3898800).

Almost surely, 2^667691640 is an apocalyptic number.

667691640 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 667691640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1497139200).

667691640 is an abundant number, since it is smaller than the sum of its proper divisors (2326586760).

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

667691640 is a wasteful number, since it uses less digits than its factorization.

667691640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113 (or 96 counting only the distinct ones).

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

The square root of 667691640 is about 25839.7298747491. The cubic root of 667691640 is about 874.0279338331.

The spelling of 667691640 in words is "six hundred sixty-seven million, six hundred ninety-one thousand, six hundred forty".