121640681 has 4 divisors (see below), whose sum is σ = 121662852. Its totient is φ = 121618512.

The previous prime is 121640677. The next prime is 121640741. The reversal of 121640681 is 186046121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186046121 = 73 ⋅2548577.

It can be written as a sum of positive squares in 2 ways, for example, as 47955625 + 73685056 = 6925^2 + 8584^2 .

It is a cyclic number.

It is not a de Polignac number, because 121640681 - 2² = 121640677 is a prime.

It is a super-2 number, since 2×121640681² = 29592910548287522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121640611) 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, 3875 + ... + 16071.

It is an arithmetic number, because the mean of its divisors is an integer number (30415713).

Almost surely, 2^121640681 is an apocalyptic number.

It is an amenable number.

121640681 is a deficient number, since it is larger than the sum of its proper divisors (22171).

121640681 is an equidigital number, since it uses as much as digits as its factorization.

121640681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22170.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 121640681 is about 11029.0834161321. The cubic root of 121640681 is about 495.4801734489.

The spelling of 121640681 in words is "one hundred twenty-one million, six hundred forty thousand, six hundred eighty-one".