121661657 has 4 divisors (see below), whose sum is σ = 131020260. Its totient is φ = 112303056.

The previous prime is 121661647. The next prime is 121661669. The reversal of 121661657 is 756166121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 81072016 + 40589641 = 9004^2 + 6371^2 .

It is a cyclic number.

It is not a de Polignac number, because 121661657 - 2⁶ = 121661593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121661647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4679282 + ... + 4679307.

It is an arithmetic number, because the mean of its divisors is an integer number (32755065).

Almost surely, 2^121661657 is an apocalyptic number.

It is an amenable number.

121661657 is a deficient number, since it is larger than the sum of its proper divisors (9358603).

121661657 is an equidigital number, since it uses as much as digits as its factorization.

121661657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9358602.

The product of its digits is 15120, while the sum is 35.

The square root of 121661657 is about 11030.0343154498. The cubic root of 121661657 is about 495.5086523939.

The spelling of 121661657 in words is "one hundred twenty-one million, six hundred sixty-one thousand, six hundred fifty-seven".