687336021 has 6 divisors (see below), whose sum is σ = 992818710. Its totient is φ = 458224008.

The previous prime is 687335981. The next prime is 687336079. The reversal of 687336021 is 120633786.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 671535396 + 15800625 = 25914^2 + 3975^2 .

It is not a de Polignac number, because 687336021 - 2⁷ = 687335893 is a prime.

It is a super-2 number, since 2×687336021² = 944861611528224882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687336121) 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, 38185326 + ... + 38185343.

It is an arithmetic number, because the mean of its divisors is an integer number (165469785).

Almost surely, 2^687336021 is an apocalyptic number.

It is an amenable number.

687336021 is a deficient number, since it is larger than the sum of its proper divisors (305482689).

687336021 is a wasteful number, since it uses less digits than its factorization.

687336021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76370675 (or 76370672 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 687336021 is about 26217.0940609367. The cubic root of 687336021 is about 882.5169081926.

The spelling of 687336021 in words is "six hundred eighty-seven million, three hundred thirty-six thousand, twenty-one".