1997235840 has 64 divisors (see below), whose sum is σ = 6366195360. Its totient is φ = 532595712.

The previous prime is 1997235833. The next prime is 1997235847. The reversal of 1997235840 is 485327991.

It is an interprime number because it is at equal distance from previous prime (1997235833) and next prime (1997235847).

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 1997235840.

It is not an unprimeable number, because it can be changed into a prime (1997235847) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 518194 + ... + 522033.

Almost surely, 2^1997235840 is an apocalyptic number.

1997235840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1997235840 is an abundant number, since it is smaller than the sum of its proper divisors (4368959520).

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

1997235840 is a wasteful number, since it uses less digits than its factorization.

1997235840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040249 (or 1040237 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 48.

The square root of 1997235840 is about 44690.4446162712. Note that the first 3 decimals coincide. The cubic root of 1997235840 is about 1259.3403450576.

The spelling of 1997235840 in words is "one billion, nine hundred ninety-seven million, two hundred thirty-five thousand, eight hundred forty".