121681913 has 4 divisors (see below), whose sum is σ = 125607168. Its totient is φ = 117756660.

The previous prime is 121681907. The next prime is 121681921. The reversal of 121681913 is 319186121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 121681913 - 2¹⁸ = 121419769 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 121681913.

It is not an unprimeable number, because it can be changed into a prime (121681943) 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, 1962581 + ... + 1962642.

It is an arithmetic number, because the mean of its divisors is an integer number (31401792).

Almost surely, 2^121681913 is an apocalyptic number.

It is an amenable number.

121681913 is a deficient number, since it is larger than the sum of its proper divisors (3925255).

121681913 is an equidigital number, since it uses as much as digits as its factorization.

121681913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3925254.

The product of its digits is 2592, while the sum is 32.

The square root of 121681913 is about 11030.9524974047. The cubic root of 121681913 is about 495.5361506940.

The spelling of 121681913 in words is "one hundred twenty-one million, six hundred eighty-one thousand, nine hundred thirteen".