16121581251 has 4 divisors (see below), whose sum is σ = 21495441672. Its totient is φ = 10747720832.

The previous prime is 16121581243. The next prime is 16121581297. The reversal of 16121581251 is 15218512161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16121581251 - 2³ = 16121581243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16121581211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2686930206 + ... + 2686930211.

It is an arithmetic number, because the mean of its divisors is an integer number (5373860418).

Almost surely, 2^16121581251 is an apocalyptic number.

16121581251 is a deficient number, since it is larger than the sum of its proper divisors (5373860421).

16121581251 is an equidigital number, since it uses as much as digits as its factorization.

16121581251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5373860420.

The product of its digits is 4800, while the sum is 33.

The spelling of 16121581251 in words is "sixteen billion, one hundred twenty-one million, five hundred eighty-one thousand, two hundred fifty-one".