121664691 has 24 divisors (see below), whose sum is σ = 178860240. Its totient is φ = 79681536.

The previous prime is 121664663. The next prime is 121664731. The reversal of 121664691 is 196466121.

121664691 is a `hidden beast` number, since 1 + 2 + 1 + 6 + 646 + 9 + 1 = 666.

It is not a de Polignac number, because 121664691 - 2⁵ = 121664659 is a prime.

It is a super-2 number, since 2×121664691² = 29604594072250962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (121664651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 154200 + ... + 154986.

It is an arithmetic number, because the mean of its divisors is an integer number (7452510).

Almost surely, 2^121664691 is an apocalyptic number.

121664691 is a deficient number, since it is larger than the sum of its proper divisors (57195549).

121664691 is a wasteful number, since it uses less digits than its factorization.

121664691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075 (or 1072 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 121664691 is about 11030.1718481627. The cubic root of 121664691 is about 495.5127713601.

The spelling of 121664691 in words is "one hundred twenty-one million, six hundred sixty-four thousand, six hundred ninety-one".