690790721 has 4 divisors (see below), whose sum is σ = 692350512. Its totient is φ = 689230932.

The previous prime is 690790697. The next prime is 690790729. The reversal of 690790721 is 127097096.

It is a happy number.

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 690790721 - 2¹⁸ = 690528577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (690790729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 779231 + ... + 780116.

It is an arithmetic number, because the mean of its divisors is an integer number (173087628).

Almost surely, 2^690790721 is an apocalyptic number.

It is an amenable number.

690790721 is a deficient number, since it is larger than the sum of its proper divisors (1559791).

690790721 is a wasteful number, since it uses less digits than its factorization.

690790721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1559790.

The product of its (nonzero) digits is 47628, while the sum is 41.

The square root of 690790721 is about 26282.8978805610. The cubic root of 690790721 is about 883.9930117074.

The spelling of 690790721 in words is "six hundred ninety million, seven hundred ninety thousand, seven hundred twenty-one".