13421256581 has 2 divisors, whose sum is σ = 13421256582. Its totient is φ = 13421256580.

The previous prime is 13421256559. The next prime is 13421256623. The reversal of 13421256581 is 18565212431.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8271902500 + 5149354081 = 90950^2 + 71759^2 .

It is a cyclic number.

It is not a de Polignac number, because 13421256581 - 2³⁰ = 12347514757 is a prime.

It is a super-2 number, since 2×13421256581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13421255581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6710628290 + 6710628291.

It is an arithmetic number, because the mean of its divisors is an integer number (6710628291).

Almost surely, 2^13421256581 is an apocalyptic number.

It is an amenable number.

13421256581 is a deficient number, since it is larger than the sum of its proper divisors (1).

13421256581 is an equidigital number, since it uses as much as digits as its factorization.

13421256581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 57600, while the sum is 38.

The spelling of 13421256581 in words is "thirteen billion, four hundred twenty-one million, two hundred fifty-six thousand, five hundred eighty-one".