668075640 has 32 divisors (see below), whose sum is σ = 2004227280. Its totient is φ = 178153472.

The previous prime is 668075623. The next prime is 668075647. The reversal of 668075640 is 46570866.

It is a happy number.

It is a super-2 number, since 2×668075640² = 892650121522819200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 668075592 and 668075601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668075647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2783529 + ... + 2783768.

Almost surely, 2^668075640 is an apocalyptic number.

668075640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

668075640 is an abundant number, since it is smaller than the sum of its proper divisors (1336151640).

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

668075640 is a wasteful number, since it uses less digits than its factorization.

668075640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5567311 (or 5567307 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The square root of 668075640 is about 25847.1592249516. The cubic root of 668075640 is about 874.1954574750.

The spelling of 668075640 in words is "six hundred sixty-eight million, seventy-five thousand, six hundred forty".