1251020509 has 2 divisors, whose sum is σ = 1251020510. Its totient is φ = 1251020508.

The previous prime is 1251020467. The next prime is 1251020527. The reversal of 1251020509 is 9050201521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1249976025 + 1044484 = 35355^2 + 1022^2 .

It is an emirp because it is prime and its reverse (9050201521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1251020509 - 2¹³ = 1251012317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1251020549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625510254 + 625510255.

It is an arithmetic number, because the mean of its divisors is an integer number (625510255).

Almost surely, 2^1251020509 is an apocalyptic number.

It is an amenable number.

1251020509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251020509 is an equidigital number, since it uses as much as digits as its factorization.

1251020509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 1251020509 is about 35369.7682915792. The cubic root of 1251020509 is about 1077.5104146078.

The spelling of 1251020509 in words is "one billion, two hundred fifty-one million, twenty thousand, five hundred nine".