668728092554 has 4 divisors (see below), whose sum is σ = 1003092138834. Its totient is φ = 334364046276.

The previous prime is 668728092553. The next prime is 668728092589. The reversal of 668728092554 is 455290827866.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 616974117529 + 51753975025 = 785477^2 + 227495^2 .

It is a super-2 number, since 2×668728092554² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (668728092551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167182023137 + ... + 167182023140.

Almost surely, 2^668728092554 is an apocalyptic number.

668728092554 is a deficient number, since it is larger than the sum of its proper divisors (334364046280).

668728092554 is a wasteful number, since it uses less digits than its factorization.

668728092554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334364046279.

The product of its (nonzero) digits is 58060800, while the sum is 62.

The spelling of 668728092554 in words is "six hundred sixty-eight billion, seven hundred twenty-eight million, ninety-two thousand, five hundred fifty-four".