21253365513121 has 6 divisors (see below), whose sum is σ = 24723302739810. Its totient is φ = 18217170439776.

The previous prime is 21253365513091. The next prime is 21253365513173. The reversal of 21253365513121 is 12131556335212.

It can be written as a sum of positive squares in only one way, i.e., 11188222214400 + 10065143298721 = 3344880^2 + 3172561^2 .

It is not a de Polignac number, because 21253365513121 - 2⁵ = 21253365513089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21253365513221) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 216871076616 + ... + 216871076713.

It is an arithmetic number, because the mean of its divisors is an integer number (4120550456635).

Almost surely, 2^{21253365513121} is an apocalyptic number.

It is an amenable number.

21253365513121 is a deficient number, since it is larger than the sum of its proper divisors (3469937226689).

21253365513121 is an equidigital number, since it uses as much as digits as its factorization.

21253365513121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 433742153343 (or 433742153336 counting only the distinct ones).

The product of its digits is 162000, while the sum is 40.

The spelling of 21253365513121 in words is "twenty-one trillion, two hundred fifty-three billion, three hundred sixty-five million, five hundred thirteen thousand, one hundred twenty-one".