997613981 has 48 divisors (see below), whose sum is σ = 1327233600. Its totient is φ = 741146112.

The previous prime is 997613951. The next prime is 997613993. The reversal of 997613981 is 189316799.

It is not a de Polignac number, because 997613981 - 2⁶ = 997613917 is a prime.

It is a super-2 number, since 2×997613981² = 1990467310173336722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997613951) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1682021 + ... + 1682613.

It is an arithmetic number, because the mean of its divisors is an integer number (27650700).

Almost surely, 2^997613981 is an apocalyptic number.

997613981 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

997613981 is a deficient number, since it is larger than the sum of its proper divisors (329619619).

997613981 is a wasteful number, since it uses less digits than its factorization.

997613981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778 (or 771 counting only the distinct ones).

The product of its digits is 734832, while the sum is 53.

The square root of 997613981 is about 31585.0277979931. The cubic root of 997613981 is about 999.2040269283.

The spelling of 997613981 in words is "nine hundred ninety-seven million, six hundred thirteen thousand, nine hundred eighty-one".