668638154 has 4 divisors (see below), whose sum is σ = 1002957234. Its totient is φ = 334319076.

The previous prime is 668638153. The next prime is 668638183. The reversal of 668638154 is 451836866.

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., 618865129 + 49773025 = 24877^2 + 7055^2 .

It is a junction number, because it is equal to n+sod(n) for n = 668638099 and 668638108.

It is not an unprimeable number, because it can be changed into a prime (668638151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167159537 + ... + 167159540.

Almost surely, 2^668638154 is an apocalyptic number.

668638154 is a deficient number, since it is larger than the sum of its proper divisors (334319080).

668638154 is a wasteful number, since it uses less digits than its factorization.

668638154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334319079.

The product of its digits is 829440, while the sum is 47.

The square root of 668638154 is about 25858.0384793588. The cubic root of 668638154 is about 874.4407436887.

The spelling of 668638154 in words is "six hundred sixty-eight million, six hundred thirty-eight thousand, one hundred fifty-four".