121655681 has 6 divisors (see below), whose sum is σ = 141517890. Its totient is φ = 104276256.

The previous prime is 121655657. The next prime is 121655753. The reversal of 121655681 is 186556121.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 112169281 + 9486400 = 10591^2 + 3080^2 .

It is a de Polignac number, because none of the positive numbers 2^k-121655681 is a prime.

It is a super-2 number, since 2×121655681² = 29600209439147522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121657681) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1241336 + ... + 1241433.

It is an arithmetic number, because the mean of its divisors is an integer number (23586315).

Almost surely, 2^121655681 is an apocalyptic number.

It is an amenable number.

121655681 is a deficient number, since it is larger than the sum of its proper divisors (19862209).

121655681 is an equidigital number, since it uses as much as digits as its factorization.

121655681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2482783 (or 2482776 counting only the distinct ones).

The product of its digits is 14400, while the sum is 35.

The square root of 121655681 is about 11029.7634154138. The cubic root of 121655681 is about 495.5005391606.

The spelling of 121655681 in words is "one hundred twenty-one million, six hundred fifty-five thousand, six hundred eighty-one".