81211379 has 2 divisors, whose sum is σ = 81211380. Its totient is φ = 81211378.

The previous prime is 81211349. The next prime is 81211387. The reversal of 81211379 is 97311218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81211379 - 2²⁴ = 64434163 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81211309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40605689 + 40605690.

It is an arithmetic number, because the mean of its divisors is an integer number (40605690).

Almost surely, 2^81211379 is an apocalyptic number.

81211379 is a deficient number, since it is larger than the sum of its proper divisors (1).

81211379 is an equidigital number, since it uses as much as digits as its factorization.

81211379 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 32.

The square root of 81211379 is about 9011.7356263930. The cubic root of 81211379 is about 433.0509161111.

The spelling of 81211379 in words is "eighty-one million, two hundred eleven thousand, three hundred seventy-nine".