121685851 has 4 divisors (see below), whose sum is σ = 139069552. Its totient is φ = 104302152.

The previous prime is 121685797. The next prime is 121685891. The reversal of 121685851 is 158586121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 158586121 = 113 ⋅1403417.

It is a cyclic number.

It is not a de Polignac number, because 121685851 - 2¹⁹ = 121161563 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 121685851.

It is not an unprimeable number, because it can be changed into a prime (121685891) 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, 8691840 + ... + 8691853.

It is an arithmetic number, because the mean of its divisors is an integer number (34767388).

Almost surely, 2^121685851 is an apocalyptic number.

121685851 is a deficient number, since it is larger than the sum of its proper divisors (17383701).

121685851 is an equidigital number, since it uses as much as digits as its factorization.

121685851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17383700.

The product of its digits is 19200, while the sum is 37.

The square root of 121685851 is about 11031.1309936924. The cubic root of 121685851 is about 495.5414963263.

The spelling of 121685851 in words is "one hundred twenty-one million, six hundred eighty-five thousand, eight hundred fifty-one".