997809138 has 32 divisors (see below), whose sum is σ = 2313763200. Its totient is φ = 318141648.

The previous prime is 997809103. The next prime is 997809139. The reversal of 997809138 is 831908799.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (997809139) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 400453 + ... + 402936.

It is an arithmetic number, because the mean of its divisors is an integer number (72305100).

Almost surely, 2^997809138 is an apocalyptic number.

997809138 is an abundant number, since it is smaller than the sum of its proper divisors (1315954062).

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

997809138 is a wasteful number, since it uses less digits than its factorization.

997809138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 803423 (or 803417 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The square root of 997809138 is about 31588.1170378989. The cubic root of 997809138 is about 999.2691786970.

The spelling of 997809138 in words is "nine hundred ninety-seven million, eight hundred nine thousand, one hundred thirty-eight".