1557121403 has 2 divisors, whose sum is σ = 1557121404. Its totient is φ = 1557121402.

The previous prime is 1557121387. The next prime is 1557121427. The reversal of 1557121403 is 3041217551.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1557121403 - 2⁴ = 1557121387 is a prime.

It is not a weakly prime, because it can be changed into another prime (1557121603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 778560701 + 778560702.

It is an arithmetic number, because the mean of its divisors is an integer number (778560702).

Almost surely, 2^1557121403 is an apocalyptic number.

1557121403 is a deficient number, since it is larger than the sum of its proper divisors (1).

1557121403 is an equidigital number, since it uses as much as digits as its factorization.

1557121403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 1557121403 is about 39460.3776337733. The cubic root of 1557121403 is about 1159.0641984488.

Adding to 1557121403 its reverse (3041217551), we get a palindrome (4598338954).

The spelling of 1557121403 in words is "one billion, five hundred fifty-seven million, one hundred twenty-one thousand, four hundred three".