1981931990 has 32 divisors (see below), whose sum is σ = 3876387840. Its totient is φ = 726818400.

The previous prime is 1981931983. The next prime is 1981931999. The reversal of 1981931990 is 991391891.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981931999) 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, 162356 + ... + 174135.

It is an arithmetic number, because the mean of its divisors is an integer number (121137120).

Almost surely, 2^1981931990 is an apocalyptic number.

1981931990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1981931990 is a deficient number, since it is larger than the sum of its proper divisors (1894455850).

1981931990 is a wasteful number, since it uses less digits than its factorization.

1981931990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336548.

The product of its (nonzero) digits is 157464, while the sum is 50.

The square root of 1981931990 is about 44518.8947526778. The cubic root of 1981931990 is about 1256.1155227123.

The spelling of 1981931990 in words is "one billion, nine hundred eighty-one million, nine hundred thirty-one thousand, nine hundred ninety".