251365135541 has 4 divisors (see below), whose sum is σ = 270700915212. Its totient is φ = 232029355872.

The previous prime is 251365135517. The next prime is 251365135543. The reversal of 251365135541 is 145531563152.

251365135541 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 106436452516 + 144928683025 = 326246^2 + 380695^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251365135541 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251365135543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9667889816 + ... + 9667889841.

It is an arithmetic number, because the mean of its divisors is an integer number (67675228803).

Almost surely, 2^251365135541 is an apocalyptic number.

It is an amenable number.

251365135541 is a deficient number, since it is larger than the sum of its proper divisors (19335779671).

251365135541 is a wasteful number, since it uses less digits than its factorization.

251365135541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19335779670.

The product of its digits is 270000, while the sum is 41.

Adding to 251365135541 its reverse (145531563152), we get a palindrome (396896698693).

The spelling of 251365135541 in words is "two hundred fifty-one billion, three hundred sixty-five million, one hundred thirty-five thousand, five hundred forty-one".