1981368531 has 12 divisors (see below), whose sum is σ = 2862540720. Its totient is φ = 1320652080.

The previous prime is 1981368527. The next prime is 1981368551. The reversal of 1981368531 is 1358631891.

It is a happy number.

1981368531 is a `hidden beast` number, since 1 + 9 + 81 + 36 + 8 + 531 = 666.

It is not a de Polignac number, because 1981368531 - 2² = 1981368527 is a prime.

It is a super-3 number, since 3×1981368531³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (1981368551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34066 + ... + 71576.

It is an arithmetic number, because the mean of its divisors is an integer number (238545060).

Almost surely, 2^1981368531 is an apocalyptic number.

1981368531 is a deficient number, since it is larger than the sum of its proper divisors (881172189).

1981368531 is a wasteful number, since it uses less digits than its factorization.

1981368531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43386 (or 43383 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 1981368531 is about 44512.5659898416. The cubic root of 1981368531 is about 1255.9964744499.

The spelling of 1981368531 in words is "one billion, nine hundred eighty-one million, three hundred sixty-eight thousand, five hundred thirty-one".