1981507931 has 6 divisors (see below), whose sum is σ = 2145656700. Its totient is φ = 1829084088.

The previous prime is 1981507909. The next prime is 1981507943. The reversal of 1981507931 is 1397051891.

It is not a de Polignac number, because 1981507931 - 2⁶ = 1981507867 is a prime.

It is a super-2 number, since 2×1981507931² = 7852747361231801522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981507951) 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, 5862281 + ... + 5862618.

It is an arithmetic number, because the mean of its divisors is an integer number (357609450).

Almost surely, 2^1981507931 is an apocalyptic number.

1981507931 is a deficient number, since it is larger than the sum of its proper divisors (164148769).

1981507931 is a wasteful number, since it uses less digits than its factorization.

1981507931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11724925 (or 11724912 counting only the distinct ones).

The product of its (nonzero) digits is 68040, while the sum is 44.

The square root of 1981507931 is about 44514.1318122683. The cubic root of 1981507931 is about 1256.0259291424.

The spelling of 1981507931 in words is "one billion, nine hundred eighty-one million, five hundred seven thousand, nine hundred thirty-one".