671239921 has 4 divisors (see below), whose sum is σ = 732261744. Its totient is φ = 610218100.

The previous prime is 671239901. The next prime is 671239949. The reversal of 671239921 is 129932176.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 671239921 - 2²¹ = 669142769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (671239901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30510895 + ... + 30510916.

It is an arithmetic number, because the mean of its divisors is an integer number (183065436).

Almost surely, 2^671239921 is an apocalyptic number.

It is an amenable number.

671239921 is a deficient number, since it is larger than the sum of its proper divisors (61021823).

671239921 is a wasteful number, since it uses less digits than its factorization.

671239921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61021822.

The product of its digits is 40824, while the sum is 40.

The square root of 671239921 is about 25908.2983038254. The cubic root of 671239921 is about 875.5734672290.

The spelling of 671239921 in words is "six hundred seventy-one million, two hundred thirty-nine thousand, nine hundred twenty-one".