81079861 has 2 divisors, whose sum is σ = 81079862. Its totient is φ = 81079860.

The previous prime is 81079753. The next prime is 81079927. The reversal of 81079861 is 16897018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79032100 + 2047761 = 8890^2 + 1431^2 .

It is a cyclic number.

It is not a de Polignac number, because 81079861 - 2¹¹ = 81077813 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81079261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539930 + 40539931.

It is an arithmetic number, because the mean of its divisors is an integer number (40539931).

Almost surely, 2^81079861 is an apocalyptic number.

It is an amenable number.

81079861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81079861 is an equidigital number, since it uses as much as digits as its factorization.

81079861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 81079861 is about 9004.4356291774. The cubic root of 81079861 is about 432.8170212902.

The spelling of 81079861 in words is "eighty-one million, seventy-nine thousand, eight hundred sixty-one".