1557121427 has 2 divisors, whose sum is σ = 1557121428. Its totient is φ = 1557121426.

The previous prime is 1557121403. The next prime is 1557121439. The reversal of 1557121427 is 7241217551.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1557121427 is a prime.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (1557124427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 778560713 + 778560714.

It is an arithmetic number, because the mean of its divisors is an integer number (778560714).

Almost surely, 2^1557121427 is an apocalyptic number.

1557121427 is a deficient number, since it is larger than the sum of its proper divisors (1).

1557121427 is an equidigital number, since it uses as much as digits as its factorization.

1557121427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19600, while the sum is 35.

The square root of 1557121427 is about 39460.3779378759. The cubic root of 1557121427 is about 1159.0642044037.

Adding to 1557121427 its reverse (7241217551), we get a palindrome (8798338978).

The spelling of 1557121427 in words is "one billion, five hundred fifty-seven million, one hundred twenty-one thousand, four hundred twenty-seven".