2155951215581 has 2 divisors, whose sum is σ = 2155951215582. Its totient is φ = 2155951215580.

The previous prime is 2155951215559. The next prime is 2155951215599. The reversal of 2155951215581 is 1855121595512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1715707022500 + 440244193081 = 1309850^2 + 663509^2 .

It is a cyclic number.

It is not a de Polignac number, because 2155951215581 - 2¹⁸ = 2155950953437 is a prime.

It is a super-2 number, since 2×2155951215581² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2155951275581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1077975607790 + 1077975607791.

It is an arithmetic number, because the mean of its divisors is an integer number (1077975607791).

Almost surely, 2^{2155951215581} is an apocalyptic number.

It is an amenable number.

2155951215581 is a deficient number, since it is larger than the sum of its proper divisors (1).

2155951215581 is an equidigital number, since it uses as much as digits as its factorization.

2155951215581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 900000, while the sum is 50.

The spelling of 2155951215581 in words is "two trillion, one hundred fifty-five billion, nine hundred fifty-one million, two hundred fifteen thousand, five hundred eighty-one".