1251231555403 has 4 divisors (see below), whose sum is σ = 1251233897728. Its totient is φ = 1251229213080.

The previous prime is 1251231555397. The next prime is 1251231555407. The reversal of 1251231555403 is 3045551321521.

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

It is a cyclic number.

It is not a de Polignac number, because 1251231555403 - 2²⁵ = 1251198000971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251231555407) 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, 65125 + ... + 1583257.

It is an arithmetic number, because the mean of its divisors is an integer number (312808474432).

Almost surely, 2^{1251231555403} is an apocalyptic number.

1251231555403 is a deficient number, since it is larger than the sum of its proper divisors (2342325).

1251231555403 is an equidigital number, since it uses as much as digits as its factorization.

1251231555403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2342324.

The product of its (nonzero) digits is 90000, while the sum is 37.

Adding to 1251231555403 its reverse (3045551321521), we get a palindrome (4296782876924).

The spelling of 1251231555403 in words is "one trillion, two hundred fifty-one billion, two hundred thirty-one million, five hundred fifty-five thousand, four hundred three".