2121806157 has 4 divisors (see below), whose sum is σ = 2829074880. Its totient is φ = 1414537436.

The previous prime is 2121806149. The next prime is 2121806177. The reversal of 2121806157 is 7516081212.

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 2121806157 - 2³ = 2121806149 is a prime.

It is a super-2 number, since 2×2121806157² = 9004122735766217298, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121806177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 353634357 + ... + 353634362.

It is an arithmetic number, because the mean of its divisors is an integer number (707268720).

Almost surely, 2^2121806157 is an apocalyptic number.

It is an amenable number.

2121806157 is a deficient number, since it is larger than the sum of its proper divisors (707268723).

2121806157 is an equidigital number, since it uses as much as digits as its factorization.

2121806157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707268722.

The product of its (nonzero) digits is 6720, while the sum is 33.

The square root of 2121806157 is about 46063.0671688284. The cubic root of 2121806157 is about 1284.9963727837.

Adding to 2121806157 its reverse (7516081212), we get a palindrome (9637887369).

The spelling of 2121806157 in words is "two billion, one hundred twenty-one million, eight hundred six thousand, one hundred fifty-seven".