690636209 has 4 divisors (see below), whose sum is σ = 690821616. Its totient is φ = 690450804.

The previous prime is 690636179. The next prime is 690636239. The reversal of 690636209 is 902636096.

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 an interprime number because it is at equal distance from previous prime (690636179) and next prime (690636239).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690636209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (690636239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86999 + ... + 94604.

It is an arithmetic number, because the mean of its divisors is an integer number (172705404).

Almost surely, 2^690636209 is an apocalyptic number.

It is an amenable number.

690636209 is a deficient number, since it is larger than the sum of its proper divisors (185407).

690636209 is a wasteful number, since it uses less digits than its factorization.

690636209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185406.

The product of its (nonzero) digits is 104976, while the sum is 41.

The square root of 690636209 is about 26279.9583142744. The cubic root of 690636209 is about 883.9270980093.

The spelling of 690636209 in words is "six hundred ninety million, six hundred thirty-six thousand, two hundred nine".