699165217921 has 3 divisors (see below), whose sum is σ = 699166054083. Its totient is φ = 699164381760.

The previous prime is 699165217909. The next prime is 699165217931. The reversal of 699165217921 is 129712561996.

The square root of 699165217921 is 836161.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 59677115521 + 639488102400 = 244289^2 + 799680^2 .

It is not a de Polignac number, because 699165217921 - 2²⁹ = 698628347009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (699165217931) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 418081 + ... + 1254241.

It is an arithmetic number, because the mean of its divisors is an integer number (233055351361).

Almost surely, 2^699165217921 is an apocalyptic number.

699165217921 is the 836161-st square number.

699165217921 is the 418081-st centered octagonal number.

It is an amenable number.

699165217921 is a deficient number, since it is larger than the sum of its proper divisors (836162).

699165217921 is an frugal number, since it uses more digits than its factorization.

699165217921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1672322 (or 836161 counting only the distinct ones).

The product of its digits is 3674160, while the sum is 58.

The spelling of 699165217921 in words is "six hundred ninety-nine billion, one hundred sixty-five million, two hundred seventeen thousand, nine hundred twenty-one".