21557474152121 has 4 divisors (see below), whose sum is σ = 21561870949632. Its totient is φ = 21553077354612.

The previous prime is 21557474152099. The next prime is 21557474152177. The reversal of 21557474152121 is 12125147475512.

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 21557474152121 - 2¹⁰ = 21557474151097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21557474151121) 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, 2198391401 + ... + 2198401206.

It is an arithmetic number, because the mean of its divisors is an integer number (5390467737408).

Almost surely, 2^{21557474152121} is an apocalyptic number.

It is an amenable number.

21557474152121 is a deficient number, since it is larger than the sum of its proper divisors (4396797511).

21557474152121 is an equidigital number, since it uses as much as digits as its factorization.

21557474152121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4396797510.

The product of its digits is 784000, while the sum is 47.

The spelling of 21557474152121 in words is "twenty-one trillion, five hundred fifty-seven billion, four hundred seventy-four million, one hundred fifty-two thousand, one hundred twenty-one".