1242551399 has 2 divisors, whose sum is σ = 1242551400. Its totient is φ = 1242551398.

The previous prime is 1242551357. The next prime is 1242551461. The reversal of 1242551399 is 9931552421.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1242551399 - 2²⁸ = 974115943 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1242551329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621275699 + 621275700.

It is an arithmetic number, because the mean of its divisors is an integer number (621275700).

Almost surely, 2^1242551399 is an apocalyptic number.

1242551399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1242551399 is an equidigital number, since it uses as much as digits as its factorization.

1242551399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 41.

The square root of 1242551399 is about 35249.8425386554. The cubic root of 1242551399 is about 1075.0734109593.

The spelling of 1242551399 in words is "one billion, two hundred forty-two million, five hundred fifty-one thousand, three hundred ninety-nine".