21154555291 has 2 divisors, whose sum is σ = 21154555292. Its totient is φ = 21154555290.

The previous prime is 21154555259. The next prime is 21154555349. The reversal of 21154555291 is 19255545112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21154555291 - 2⁵ = 21154555259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21154555211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577277645 + 10577277646.

It is an arithmetic number, because the mean of its divisors is an integer number (10577277646).

Almost surely, 2^21154555291 is an apocalyptic number.

21154555291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154555291 is an equidigital number, since it uses as much as digits as its factorization.

21154555291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90000, while the sum is 40.

The spelling of 21154555291 in words is "twenty-one billion, one hundred fifty-four million, five hundred fifty-five thousand, two hundred ninety-one".