997819878 has 128 divisors (see below), whose sum is σ = 2368880640. Its totient is φ = 277200000.

The previous prime is 997819853. The next prime is 997819897. The reversal of 997819878 is 878918799.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3975253 + ... + 3975503.

It is an arithmetic number, because the mean of its divisors is an integer number (18506880).

Almost surely, 2^997819878 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 997819878, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1184440320).

997819878 is an abundant number, since it is smaller than the sum of its proper divisors (1371060762).

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

997819878 is a wasteful number, since it uses less digits than its factorization.

997819878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394.

The product of its digits is 18289152, while the sum is 66.

The square root of 997819878 is about 31588.2870380779. The cubic root of 997819878 is about 999.2727639226.

The spelling of 997819878 in words is "nine hundred ninety-seven million, eight hundred nineteen thousand, eight hundred seventy-eight".