1553858561 has 2 divisors, whose sum is σ = 1553858562. Its totient is φ = 1553858560.

The previous prime is 1553858519. The next prime is 1553858591. The reversal of 1553858561 is 1658583551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1111555600 + 442302961 = 33340^2 + 21031^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1553858561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1553858591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 776929280 + 776929281.

It is an arithmetic number, because the mean of its divisors is an integer number (776929281).

It is a Proth number, since it is equal to 11855 ⋅ 2¹⁷ + 1 and 11855 < 2¹⁷.

Almost surely, 2^1553858561 is an apocalyptic number.

It is an amenable number.

1553858561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1553858561 is an equidigital number, since it uses as much as digits as its factorization.

1553858561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 720000, while the sum is 47.

The square root of 1553858561 is about 39419.0126842365. The cubic root of 1553858561 is about 1158.2540522497.

The spelling of 1553858561 in words is "one billion, five hundred fifty-three million, eight hundred fifty-eight thousand, five hundred sixty-one".