251250778329409 has 2 divisors, whose sum is σ = 251250778329410. Its totient is φ = 251250778329408.

The previous prime is 251250778329347. The next prime is 251250778329451. The reversal of 251250778329409 is 904923877052152.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 250065517171600 + 1185261157809 = 15813460^2 + 1088697^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-251250778329409 is a prime.

It is a super-2 number, since 2×251250778329409² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (251250778329479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125625389164704 + 125625389164705.

It is an arithmetic number, because the mean of its divisors is an integer number (125625389164705).

Almost surely, 2^{251250778329409} is an apocalyptic number.

It is an amenable number.

251250778329409 is a deficient number, since it is larger than the sum of its proper divisors (1).

251250778329409 is an equidigital number, since it uses as much as digits as its factorization.

251250778329409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 76204800, while the sum is 64.

The spelling of 251250778329409 in words is "two hundred fifty-one trillion, two hundred fifty billion, seven hundred seventy-eight million, three hundred twenty-nine thousand, four hundred nine".