690947651521 has 2 divisors, whose sum is σ = 690947651522. Its totient is φ = 690947651520.

The previous prime is 690947651477. The next prime is 690947651567. The reversal of 690947651521 is 125156749096.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 632762975296 + 58184676225 = 795464^2 + 241215^2 .

It is a cyclic number.

It is not a de Polignac number, because 690947651521 - 2²³ = 690939262913 is a prime.

It is a super-2 number, since 2×690947651521² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (690947651621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345473825760 + 345473825761.

It is an arithmetic number, because the mean of its divisors is an integer number (345473825761).

Almost surely, 2^690947651521 is an apocalyptic number.

It is an amenable number.

690947651521 is a deficient number, since it is larger than the sum of its proper divisors (1).

690947651521 is an equidigital number, since it uses as much as digits as its factorization.

690947651521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4082400, while the sum is 55.

The spelling of 690947651521 in words is "six hundred ninety billion, nine hundred forty-seven million, six hundred fifty-one thousand, five hundred twenty-one".