121805851 has 4 divisors (see below), whose sum is σ = 125735104. Its totient is φ = 117876600.

The previous prime is 121805791. The next prime is 121805891. The reversal of 121805851 is 158508121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 158508121 = 3361 ⋅47161.

It is a cyclic number.

It is not a de Polignac number, because 121805851 - 2⁹ = 121805339 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 3929221 = 121805851 / (1 + 2 + 1 + 8 + 0 + 5 + 8 + 5 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121805891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1964580 + ... + 1964641.

It is an arithmetic number, because the mean of its divisors is an integer number (31433776).

Almost surely, 2^121805851 is an apocalyptic number.

121805851 is a deficient number, since it is larger than the sum of its proper divisors (3929253).

121805851 is an equidigital number, since it uses as much as digits as its factorization.

121805851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3929252.

The product of its (nonzero) digits is 3200, while the sum is 31.

The square root of 121805851 is about 11036.5688055663. The cubic root of 121805851 is about 495.7043348780.

The spelling of 121805851 in words is "one hundred twenty-one million, eight hundred five thousand, eight hundred fifty-one".