1987191631 has 4 divisors (see below), whose sum is σ = 2029472352. Its totient is φ = 1944910912.

The previous prime is 1987191553. The next prime is 1987191643. The reversal of 1987191631 is 1361917891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1987191631 - 2⁹ = 1987191119 is a prime.

It is a super-2 number, since 2×1987191631² = 7897861156632880322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987191131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21140290 + ... + 21140383.

It is an arithmetic number, because the mean of its divisors is an integer number (507368088).

Almost surely, 2^1987191631 is an apocalyptic number.

1987191631 is a deficient number, since it is larger than the sum of its proper divisors (42280721).

1987191631 is an equidigital number, since it uses as much as digits as its factorization.

1987191631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42280720.

The product of its digits is 81648, while the sum is 46.

The square root of 1987191631 is about 44577.9276211894. The cubic root of 1987191631 is about 1257.2256988852.

The spelling of 1987191631 in words is "one billion, nine hundred eighty-seven million, one hundred ninety-one thousand, six hundred thirty-one".