687752981 has 2 divisors, whose sum is σ = 687752982. Its totient is φ = 687752980.

The previous prime is 687752977. The next prime is 687752987. The reversal of 687752981 is 189257786.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 517972081 + 169780900 = 22759^2 + 13030^2 .

It is a cyclic number.

It is not a de Polignac number, because 687752981 - 2² = 687752977 is a prime.

It is a super-2 number, since 2×687752981² = 946008325748772722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687752987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343876490 + 343876491.

It is an arithmetic number, because the mean of its divisors is an integer number (343876491).

Almost surely, 2^687752981 is an apocalyptic number.

It is an amenable number.

687752981 is a deficient number, since it is larger than the sum of its proper divisors (1).

687752981 is an equidigital number, since it uses as much as digits as its factorization.

687752981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1693440, while the sum is 53.

The square root of 687752981 is about 26225.0449189320. The cubic root of 687752981 is about 882.6953264410.

The spelling of 687752981 in words is "six hundred eighty-seven million, seven hundred fifty-two thousand, nine hundred eighty-one".