27815537861 has 2 divisors, whose sum is σ = 27815537862. Its totient is φ = 27815537860.

The previous prime is 27815537821. The next prime is 27815537881. The reversal of 27815537861 is 16873551872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15269297761 + 12546240100 = 123569^2 + 112010^2 .

It is a cyclic number.

It is not a de Polignac number, because 27815537861 - 2¹⁸ = 27815275717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27815537821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13907768930 + 13907768931.

It is an arithmetic number, because the mean of its divisors is an integer number (13907768931).

Almost surely, 2^27815537861 is an apocalyptic number.

It is an amenable number.

27815537861 is a deficient number, since it is larger than the sum of its proper divisors (1).

27815537861 is an equidigital number, since it uses as much as digits as its factorization.

27815537861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2822400, while the sum is 53.

The spelling of 27815537861 in words is "twenty-seven billion, eight hundred fifteen million, five hundred thirty-seven thousand, eight hundred sixty-one".