1161615981 has 4 divisors (see below), whose sum is σ = 1548821312. Its totient is φ = 774410652.

The previous prime is 1161615953. The next prime is 1161615991. The reversal of 1161615981 is 1895161611.

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 not a de Polignac number, because 1161615981 - 2¹¹ = 1161613933 is a prime.

It is a super-2 number, since 2×1161615981² = 2698703374629184722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1161615991) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 193602661 + ... + 193602666.

It is an arithmetic number, because the mean of its divisors is an integer number (387205328).

Almost surely, 2^1161615981 is an apocalyptic number.

It is an amenable number.

1161615981 is a deficient number, since it is larger than the sum of its proper divisors (387205331).

1161615981 is an equidigital number, since it uses as much as digits as its factorization.

1161615981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387205330.

The product of its digits is 12960, while the sum is 39.

The square root of 1161615981 is about 34082.4878933449. The cubic root of 1161615981 is about 1051.2052617937.

The spelling of 1161615981 in words is "one billion, one hundred sixty-one million, six hundred fifteen thousand, nine hundred eighty-one".