1981961915 has 32 divisors (see below), whose sum is σ = 2680776000. Its totient is φ = 1397772288.

The previous prime is 1981961879. The next prime is 1981961921. The reversal of 1981961915 is 5191691891.

It is a cyclic number.

It is not a de Polignac number, because 1981961915 - 2²⁶ = 1914853051 is a prime.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 136841 + ... + 150629.

It is an arithmetic number, because the mean of its divisors is an integer number (83774250).

Almost surely, 2^1981961915 is an apocalyptic number.

1981961915 is a deficient number, since it is larger than the sum of its proper divisors (698814085).

1981961915 is a wasteful number, since it uses less digits than its factorization.

1981961915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13919.

The product of its digits is 174960, while the sum is 50.

The square root of 1981961915 is about 44519.2308446586. The cubic root of 1981961915 is about 1256.1218446696.

The spelling of 1981961915 in words is "one billion, nine hundred eighty-one million, nine hundred sixty-one thousand, nine hundred fifteen".