1251543121326 has 80 divisors (see below), whose sum is σ = 2845737861120. Its totient is φ = 411036852240.

The previous prime is 1251543121249. The next prime is 1251543121349. The reversal of 1251543121326 is 6231213451521.

1251543121326 is a `hidden beast` number, since 1 + 2 + 5 + 1 + 5 + 431 + 213 + 2 + 6 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 17988915 + ... + 18058353.

It is an arithmetic number, because the mean of its divisors is an integer number (35571723264).

Almost surely, 2^{1251543121326} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1251543121326, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1422868930560).

1251543121326 is an abundant number, since it is smaller than the sum of its proper divisors (1594194739794).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1251543121326 is a wasteful number, since it uses less digits than its factorization.

1251543121326 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71091 (or 71082 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

Adding to 1251543121326 its reverse (6231213451521), we get a palindrome (7482756572847).

The spelling of 1251543121326 in words is "one trillion, two hundred fifty-one billion, five hundred forty-three million, one hundred twenty-one thousand, three hundred twenty-six".