81216199 has 2 divisors, whose sum is σ = 81216200. Its totient is φ = 81216198.

The previous prime is 81216133. The next prime is 81216209. The reversal of 81216199 is 99161218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81216199 - 2¹⁷ = 81085127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81216899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40608099 + 40608100.

It is an arithmetic number, because the mean of its divisors is an integer number (40608100).

Almost surely, 2^81216199 is an apocalyptic number.

81216199 is a deficient number, since it is larger than the sum of its proper divisors (1).

81216199 is an equidigital number, since it uses as much as digits as its factorization.

81216199 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 37.

The square root of 81216199 is about 9012.0030514864. The cubic root of 81216199 is about 433.0594833183.

The spelling of 81216199 in words is "eighty-one million, two hundred sixteen thousand, one hundred ninety-nine".