121647681 has 6 divisors (see below), whose sum is σ = 175713330. Its totient is φ = 81098448.

The previous prime is 121647677. The next prime is 121647719. The reversal of 121647681 is 186746121.

It is a happy number.

121647681 is a `hidden beast` number, since 1 + 2 + 1 + 647 + 6 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 118461456 + 3186225 = 10884^2 + 1785^2 .

It is not a de Polignac number, because 121647681 - 2² = 121647677 is a prime.

It is a super-2 number, since 2×121647681² = 29596316585355522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (121647641) 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, 6758196 + ... + 6758213.

It is an arithmetic number, because the mean of its divisors is an integer number (29285555).

Almost surely, 2^121647681 is an apocalyptic number.

It is an amenable number.

121647681 is a deficient number, since it is larger than the sum of its proper divisors (54065649).

121647681 is a wasteful number, since it uses less digits than its factorization.

121647681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13516415 (or 13516412 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 121647681 is about 11029.4007543474. The cubic root of 121647681 is about 495.4896776561.

The spelling of 121647681 in words is "one hundred twenty-one million, six hundred forty-seven thousand, six hundred eighty-one".