990942602521 has 3 divisors (see below), whose sum is σ = 990943597983. Its totient is φ = 990941607060.

The previous prime is 990942602467. The next prime is 990942602579. The reversal of 990942602521 is 125206249099.

The square root of 990942602521 is 995461.

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., 1990921 + 990940611600 = 1411^2 + 995460^2 .

It is not a de Polignac number, because 990942602521 - 2⁹ = 990942602009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (990943602521) 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, 497731 + ... + 1493191.

It is an arithmetic number, because the mean of its divisors is an integer number (330314532661).

Almost surely, 2^990942602521 is an apocalyptic number.

990942602521 is the 995461-st square number.

990942602521 is the 497731-st centered octagonal number.

It is an amenable number.

990942602521 is a deficient number, since it is larger than the sum of its proper divisors (995462).

990942602521 is an frugal number, since it uses more digits than its factorization.

990942602521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1990922 (or 995461 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 49.

Multiplying 990942602521 by its sum of digits (49), we get a square (48556187523529 = 6968227²).

The spelling of 990942602521 in words is "nine hundred ninety billion, nine hundred forty-two million, six hundred two thousand, five hundred twenty-one".