1251761555523 has 4 divisors (see below), whose sum is σ = 1669015407368. Its totient is φ = 834507703680.

The previous prime is 1251761555479. The next prime is 1251761555567. The reversal of 1251761555523 is 3255551671521.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (1251761555479) and next prime (1251761555567).

It is not a de Polignac number, because 1251761555523 - 2²⁴ = 1251744778307 is a prime.

It is a super-2 number, since 2×1251761555523² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251761555573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 208626925918 + ... + 208626925923.

It is an arithmetic number, because the mean of its divisors is an integer number (417253851842).

Almost surely, 2^{1251761555523} is an apocalyptic number.

1251761555523 is a deficient number, since it is larger than the sum of its proper divisors (417253851845).

1251761555523 is an equidigital number, since it uses as much as digits as its factorization.

1251761555523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417253851844.

The product of its digits is 1575000, while the sum is 48.

The spelling of 1251761555523 in words is "one trillion, two hundred fifty-one billion, seven hundred sixty-one million, five hundred fifty-five thousand, five hundred twenty-three".