997971840 has 512 divisors, whose sum is σ = 3854131200. Its totient is φ = 246343680.

The previous prime is 997971839. The next prime is 997971847. The reversal of 997971840 is 48179799.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (997971847) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 32192625 + ... + 32192655.

It is an arithmetic number, because the mean of its divisors is an integer number (7527600).

Almost surely, 2^997971840 is an apocalyptic number.

997971840 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 997971840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1927065600).

997971840 is an abundant number, since it is smaller than the sum of its proper divisors (2856159360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

997971840 is an equidigital number, since it uses as much as digits as its factorization.

997971840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 1143072, while the sum is 54.

The square root of 997971840 is about 31590.6923001064. The cubic root of 997971840 is about 999.3234891029.

The spelling of 997971840 in words is "nine hundred ninety-seven million, nine hundred seventy-one thousand, eight hundred forty".