997931281 has 4 divisors (see below), whose sum is σ = 1050454000. Its totient is φ = 945408564.

The previous prime is 997931227. The next prime is 997931303. The reversal of 997931281 is 182139799.

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 a cyclic number.

It is not a de Polignac number, because 997931281 - 2²⁵ = 964376849 is a prime.

It is a super-2 number, since 2×997931281² = 1991733683196601922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (997931581) 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, 26261331 + ... + 26261368.

It is an arithmetic number, because the mean of its divisors is an integer number (262613500).

Almost surely, 2^997931281 is an apocalyptic number.

997931281 is the 14128-th centered decagonal number.

It is an amenable number.

997931281 is a deficient number, since it is larger than the sum of its proper divisors (52522719).

997931281 is a wasteful number, since it uses less digits than its factorization.

997931281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52522718.

The product of its digits is 244944, while the sum is 49.

The square root of 997931281 is about 31590.0503481713. The cubic root of 997931281 is about 999.3099509418.

The spelling of 997931281 in words is "nine hundred ninety-seven million, nine hundred thirty-one thousand, two hundred eighty-one".