680915021 has 4 divisors (see below), whose sum is σ = 685424544. Its totient is φ = 676405500.

The previous prime is 680915017. The next prime is 680915051. The reversal of 680915021 is 120519086.

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 680915021 - 2² = 680915017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (680915051) 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, 2254535 + ... + 2254836.

It is an arithmetic number, because the mean of its divisors is an integer number (171356136).

Almost surely, 2^680915021 is an apocalyptic number.

It is an amenable number.

680915021 is a deficient number, since it is larger than the sum of its proper divisors (4509523).

680915021 is a wasteful number, since it uses less digits than its factorization.

680915021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4509522.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 680915021 is about 26094.3484494248. The cubic root of 680915021 is about 879.7601881836.

The spelling of 680915021 in words is "six hundred eighty million, nine hundred fifteen thousand, twenty-one".