1988687491 has 6 divisors (see below), whose sum is σ = 2313371220. Its totient is φ = 1704589236.

The previous prime is 1988687471. The next prime is 1988687509. The reversal of 1988687491 is 1947868891.

It is not a de Polignac number, because 1988687491 - 2²⁹ = 1451816579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1988687471) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 20292681 + ... + 20292778.

It is an arithmetic number, because the mean of its divisors is an integer number (385561870).

Almost surely, 2^1988687491 is an apocalyptic number.

1988687491 is a deficient number, since it is larger than the sum of its proper divisors (324683729).

1988687491 is an equidigital number, since it uses as much as digits as its factorization.

1988687491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40585473 (or 40585466 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 61.

The square root of 1988687491 is about 44594.7024992880. The cubic root of 1988687491 is about 1257.5410789622.

The spelling of 1988687491 in words is "one billion, nine hundred eighty-eight million, six hundred eighty-seven thousand, four hundred ninety-one".