1815285601561 has 2 divisors, whose sum is σ = 1815285601562. Its totient is φ = 1815285601560.

The previous prime is 1815285601553. The next prime is 1815285601567. The reversal of 1815285601561 is 1651065825181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1710013905625 + 105271695936 = 1307675^2 + 324456^2 .

It is a cyclic number.

It is not a de Polignac number, because 1815285601561 - 2³ = 1815285601553 is a prime.

It is not a weakly prime, because it can be changed into another prime (1815285601567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 907642800780 + 907642800781.

It is an arithmetic number, because the mean of its divisors is an integer number (907642800781).

Almost surely, 2^{1815285601561} is an apocalyptic number.

It is an amenable number.

1815285601561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1815285601561 is an equidigital number, since it uses as much as digits as its factorization.

1815285601561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576000, while the sum is 49.

The spelling of 1815285601561 in words is "one trillion, eight hundred fifteen billion, two hundred eighty-five million, six hundred one thousand, five hundred sixty-one".