1251778013 has 4 divisors (see below), whose sum is σ = 1306203168. Its totient is φ = 1197352860.

The previous prime is 1251778001. The next prime is 1251778027. The reversal of 1251778013 is 3108771521.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 3108771521 = 17 ⋅182868913.

It is not a de Polignac number, because 1251778013 - 2¹⁰ = 1251776989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251778063) 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, 27212543 + ... + 27212588.

It is an arithmetic number, because the mean of its divisors is an integer number (326550792).

Almost surely, 2^1251778013 is an apocalyptic number.

It is an amenable number.

1251778013 is a deficient number, since it is larger than the sum of its proper divisors (54425155).

1251778013 is an equidigital number, since it uses as much as digits as its factorization.

1251778013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54425154.

The product of its (nonzero) digits is 11760, while the sum is 35.

The square root of 1251778013 is about 35380.4750250756. The cubic root of 1251778013 is about 1077.7278514274.

The spelling of 1251778013 in words is "one billion, two hundred fifty-one million, seven hundred seventy-eight thousand, thirteen".