1556153491 has 2 divisors, whose sum is σ = 1556153492. Its totient is φ = 1556153490.

The previous prime is 1556153461. The next prime is 1556153507. The reversal of 1556153491 is 1943516551.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1556153491 - 2²⁷ = 1421935763 is a prime.

It is a super-2 number, since 2×1556153491² = 4843227375102974162, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1556153461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 778076745 + 778076746.

It is an arithmetic number, because the mean of its divisors is an integer number (778076746).

Almost surely, 2^1556153491 is an apocalyptic number.

1556153491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1556153491 is an equidigital number, since it uses as much as digits as its factorization.

1556153491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81000, while the sum is 40.

The square root of 1556153491 is about 39448.1113743104. Note that the first 3 decimals coincide. The cubic root of 1556153491 is about 1158.8239892444.

The spelling of 1556153491 in words is "one billion, five hundred fifty-six million, one hundred fifty-three thousand, four hundred ninety-one".