121681591 has 2 divisors, whose sum is σ = 121681592. Its totient is φ = 121681590.

The previous prime is 121681589. The next prime is 121681607. The reversal of 121681591 is 195186121.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 121681591 - 2¹ = 121681589 is a prime.

Together with 121681589, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121681501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60840795 + 60840796.

It is an arithmetic number, because the mean of its divisors is an integer number (60840796).

Almost surely, 2^121681591 is an apocalyptic number.

121681591 is a deficient number, since it is larger than the sum of its proper divisors (1).

121681591 is an equidigital number, since it uses as much as digits as its factorization.

121681591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 34.

The square root of 121681591 is about 11030.9379021006. The cubic root of 121681591 is about 495.5357135905.

The spelling of 121681591 in words is "one hundred twenty-one million, six hundred eighty-one thousand, five hundred ninety-one".