997772355221 has 4 divisors (see below), whose sum is σ = 997774376172. Its totient is φ = 997770334272.

The previous prime is 997772355187. The next prime is 997772355263. The reversal of 997772355221 is 122553277799.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 114454332721 + 883318022500 = 338311^2 + 939850^2 .

It is a cyclic number.

It is not a de Polignac number, because 997772355221 - 2³⁰ = 996698613397 is a prime.

It is a super-2 number, since 2×997772355221² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997772355821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276335 + ... + 1439411.

It is an arithmetic number, because the mean of its divisors is an integer number (249443594043).

Almost surely, 2^997772355221 is an apocalyptic number.

It is an amenable number.

997772355221 is a deficient number, since it is larger than the sum of its proper divisors (2020951).

997772355221 is a wasteful number, since it uses less digits than its factorization.

997772355221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2020950.

The product of its digits is 16669800, while the sum is 59.

The spelling of 997772355221 in words is "nine hundred ninety-seven billion, seven hundred seventy-two million, three hundred fifty-five thousand, two hundred twenty-one".