1997991768 has 32 divisors (see below), whose sum is σ = 4997306160. Its totient is φ = 665687040.

The previous prime is 1997991763. The next prime is 1997991769. The reversal of 1997991768 is 8671997991.

It is a super-2 number, since 2×1997991768² = 7983942209991531648, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1997991699 and 1997991708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1997991763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36496 + ... + 72992.

Almost surely, 2^1997991768 is an apocalyptic number.

It is an amenable number.

1997991768 is an abundant number, since it is smaller than the sum of its proper divisors (2999314392).

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

1997991768 is a wasteful number, since it uses less digits than its factorization.

1997991768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38787 (or 38783 counting only the distinct ones).

The product of its digits is 15431472, while the sum is 66.

The square root of 1997991768 is about 44698.9011945484. The cubic root of 1997991768 is about 1259.4992063751.

The spelling of 1997991768 in words is "one billion, nine hundred ninety-seven million, nine hundred ninety-one thousand, seven hundred sixty-eight".