1915487981 has 4 divisors (see below), whose sum is σ = 2089623264. Its totient is φ = 1741352700.

The previous prime is 1915487969. The next prime is 1915488011. The reversal of 1915487981 is 1897845191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1915487981 - 2²² = 1911293677 is a prime.

It is a super-2 number, since 2×1915487981² = 7338188410710912722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1915487941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 87067625 + ... + 87067646.

It is an arithmetic number, because the mean of its divisors is an integer number (522405816).

Almost surely, 2^1915487981 is an apocalyptic number.

1915487981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1915487981 is a deficient number, since it is larger than the sum of its proper divisors (174135283).

1915487981 is a wasteful number, since it uses less digits than its factorization.

1915487981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174135282.

The product of its digits is 725760, while the sum is 53.

The square root of 1915487981 is about 43766.2881793739. The cubic root of 1915487981 is about 1241.9186351066.

The spelling of 1915487981 in words is "one billion, nine hundred fifteen million, four hundred eighty-seven thousand, nine hundred eighty-one".