121661566 has 16 divisors (see below), whose sum is σ = 198901584. Its totient is φ = 55473984.

The previous prime is 121661531. The next prime is 121661569. The reversal of 121661566 is 665166121.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121661569) 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 7 ways as a sum of consecutive naturals, for example, 26031 + ... + 30346.

It is an arithmetic number, because the mean of its divisors is an integer number (12431349).

Almost surely, 2^121661566 is an apocalyptic number.

121661566 is a deficient number, since it is larger than the sum of its proper divisors (77240018).

121661566 is a wasteful number, since it uses less digits than its factorization.

121661566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56475.

The product of its digits is 12960, while the sum is 34.

The square root of 121661566 is about 11030.0301903485. The cubic root of 121661566 is about 495.5085288510.

The spelling of 121661566 in words is "one hundred twenty-one million, six hundred sixty-one thousand, five hundred sixty-six".