121661001 has 64 divisors (see below), whose sum is σ = 226867200. Its totient is φ = 62596800.

The previous prime is 121660999. The next prime is 121661011. The reversal of 121661001 is 100166121.

121661001 is a `hidden beast` number, since 1 + 2 + 1 + 661 + 0 + 0 + 1 = 666.

It is not a de Polignac number, because 121661001 - 2¹ = 121660999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121661011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 288771 + ... + 289191.

It is an arithmetic number, because the mean of its divisors is an integer number (3544800).

Almost surely, 2^121661001 is an apocalyptic number.

121661001 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

121661001 is a deficient number, since it is larger than the sum of its proper divisors (105206199).

121661001 is a wasteful number, since it uses less digits than its factorization.

121661001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587 (or 581 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 121661001 is about 11030.0045784215. The cubic root of 121661001 is about 495.5077617976.

The spelling of 121661001 in words is "one hundred twenty-one million, six hundred sixty-one thousand, one".