690699721 has 2 divisors, whose sum is σ = 690699722. Its totient is φ = 690699720.

The previous prime is 690699701. The next prime is 690699791. The reversal of 690699721 is 127996096.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 422919225 + 267780496 = 20565^2 + 16364^2 .

It is a cyclic number.

It is not a de Polignac number, because 690699721 - 2¹¹ = 690697673 is a prime.

It is a super-2 number, since 2×690699721² = 954132209178955682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (690699701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345349860 + 345349861.

It is an arithmetic number, because the mean of its divisors is an integer number (345349861).

Almost surely, 2^690699721 is an apocalyptic number.

It is an amenable number.

690699721 is a deficient number, since it is larger than the sum of its proper divisors (1).

690699721 is an equidigital number, since it uses as much as digits as its factorization.

690699721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 49.

The square root of 690699721 is about 26281.1666597965. The cubic root of 690699721 is about 883.9541929575.

The spelling of 690699721 in words is "six hundred ninety million, six hundred ninety-nine thousand, seven hundred twenty-one".