1251511220403 has 12 divisors (see below), whose sum is σ = 1809401496448. Its totient is φ = 833573244240.

The previous prime is 1251511220371. The next prime is 1251511220417. The reversal of 1251511220403 is 3040221151521.

It is a happy number.

1251511220403 is a `hidden beast` number, since 1 + 25 + 1 + 5 + 11 + 220 + 403 = 666.

It is not a de Polignac number, because 1251511220403 - 2⁵ = 1251511220371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251511220473) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 63953788 + ... + 63973353.

Almost surely, 2^{1251511220403} is an apocalyptic number.

1251511220403 is a deficient number, since it is larger than the sum of its proper divisors (557890276045).

1251511220403 is a wasteful number, since it uses less digits than its factorization.

1251511220403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127928234 (or 127928231 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

Adding to 1251511220403 its reverse (3040221151521), we get a palindrome (4291732371924).

The spelling of 1251511220403 in words is "one trillion, two hundred fifty-one billion, five hundred eleven million, two hundred twenty thousand, four hundred three".