221471538157 has 4 divisors (see below), whose sum is σ = 221494387036. Its totient is φ = 221448689280.

The previous prime is 221471538137. The next prime is 221471538191. The reversal of 221471538157 is 751835174122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 751835174122 = 2 ⋅375917587061.

It can be written as a sum of positive squares in 2 ways, for example, as 133567589961 + 87903948196 = 365469^2 + 296486^2 .

It is a cyclic number.

It is not a de Polignac number, because 221471538157 - 2¹⁵ = 221471505389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221471538137) 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, 11409894 + ... + 11429287.

It is an arithmetic number, because the mean of its divisors is an integer number (55373596759).

Almost surely, 2^221471538157 is an apocalyptic number.

It is an amenable number.

221471538157 is a deficient number, since it is larger than the sum of its proper divisors (22848879).

221471538157 is an equidigital number, since it uses as much as digits as its factorization.

221471538157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22848878.

The product of its digits is 470400, while the sum is 46.

The spelling of 221471538157 in words is "two hundred twenty-one billion, four hundred seventy-one million, five hundred thirty-eight thousand, one hundred fifty-seven".