1555249681 has 2 divisors, whose sum is σ = 1555249682. Its totient is φ = 1555249680.

The previous prime is 1555249669. The next prime is 1555249691. The reversal of 1555249681 is 1869425551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1504198656 + 51051025 = 38784^2 + 7145^2 .

It is a cyclic number.

It is not a de Polignac number, because 1555249681 - 2¹¹ = 1555247633 is a prime.

It is a super-2 number, since 2×1555249681² = 4837603140501203522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1555249691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777624840 + 777624841.

It is an arithmetic number, because the mean of its divisors is an integer number (777624841).

Almost surely, 2^1555249681 is an apocalyptic number.

It is an amenable number.

1555249681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555249681 is an equidigital number, since it uses as much as digits as its factorization.

1555249681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432000, while the sum is 46.

The square root of 1555249681 is about 39436.6540289614. The cubic root of 1555249681 is about 1158.5995984525.

The spelling of 1555249681 in words is "one billion, five hundred fifty-five million, two hundred forty-nine thousand, six hundred eighty-one".