667375621 has 6 divisors (see below), whose sum is σ = 733561766. Its totient is φ = 606705000.

The previous prime is 667375603. The next prime is 667375649. The reversal of 667375621 is 126573766.

It can be written as a sum of positive squares in only one way, i.e., 640646721 + 26728900 = 25311^2 + 5170^2 .

It is not a de Polignac number, because 667375621 - 2⁷ = 667375493 is a prime.

It is a super-3 number, since 3×667375621³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667375601) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2757630 + ... + 2757871.

Almost surely, 2^667375621 is an apocalyptic number.

It is an amenable number.

667375621 is a deficient number, since it is larger than the sum of its proper divisors (66186145).

667375621 is a wasteful number, since it uses less digits than its factorization.

667375621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5515523 (or 5515512 counting only the distinct ones).

The product of its digits is 317520, while the sum is 43.

The square root of 667375621 is about 25833.6141683660. The cubic root of 667375621 is about 873.8900193602.

The spelling of 667375621 in words is "six hundred sixty-seven million, three hundred seventy-five thousand, six hundred twenty-one".