21557172139 has 4 divisors (see below), whose sum is σ = 22015835424. Its totient is φ = 21098508856.

The previous prime is 21557172137. The next prime is 21557172149. The reversal of 21557172139 is 93127175512.

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 21557172139 - 2¹ = 21557172137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21557172095 and 21557172104.

It is not an unprimeable number, because it can be changed into a prime (21557172137) 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, 229331572 + ... + 229331665.

It is an arithmetic number, because the mean of its divisors is an integer number (5503958856).

Almost surely, 2^21557172139 is an apocalyptic number.

21557172139 is a deficient number, since it is larger than the sum of its proper divisors (458663285).

21557172139 is an equidigital number, since it uses as much as digits as its factorization.

21557172139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458663284.

The product of its digits is 132300, while the sum is 43.

The spelling of 21557172139 in words is "twenty-one billion, five hundred fifty-seven million, one hundred seventy-two thousand, one hundred thirty-nine".