120991661 has 16 divisors (see below), whose sum is σ = 144862464. Its totient is φ = 98803584.

The previous prime is 120991657. The next prime is 120991679. The reversal of 120991661 is 166199021.

It is not a de Polignac number, because 120991661 - 2² = 120991657 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (120991621) 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 15 ways as a sum of consecutive naturals, for example, 43241 + ... + 45953.

It is an arithmetic number, because the mean of its divisors is an integer number (9053904).

Almost surely, 2^120991661 is an apocalyptic number.

It is an amenable number.

120991661 is a deficient number, since it is larger than the sum of its proper divisors (23870803).

120991661 is a wasteful number, since it uses less digits than its factorization.

120991661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3020.

The product of its (nonzero) digits is 5832, while the sum is 35.

The square root of 120991661 is about 10999.6209480145. The cubic root of 120991661 is about 494.5973816883.

The spelling of 120991661 in words is "one hundred twenty million, nine hundred ninety-one thousand, six hundred sixty-one".