997855631 has 4 divisors (see below), whose sum is σ = 1009878072. Its totient is φ = 985833192.

The previous prime is 997855619. The next prime is 997855633. The reversal of 997855631 is 136558799.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 136558799 = 13 ⋅10504523.

It is a cyclic number.

It is not a de Polignac number, because 997855631 - 2¹⁰ = 997854607 is a prime.

It is a super-2 number, since 2×997855631² = 1991431720636816322, which 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 (997855633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6011096 + ... + 6011261.

It is an arithmetic number, because the mean of its divisors is an integer number (252469518).

Almost surely, 2^997855631 is an apocalyptic number.

997855631 is a deficient number, since it is larger than the sum of its proper divisors (12022441).

997855631 is a wasteful number, since it uses less digits than its factorization.

997855631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12022440.

The product of its digits is 2041200, while the sum is 53.

The square root of 997855631 is about 31588.8529548004. The cubic root of 997855631 is about 999.2846987995.

The spelling of 997855631 in words is "nine hundred ninety-seven million, eight hundred fifty-five thousand, six hundred thirty-one".