81638411 has 2 divisors, whose sum is σ = 81638412. Its totient is φ = 81638410.

The previous prime is 81638399. The next prime is 81638419. The reversal of 81638411 is 11483618.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81638411 - 2¹⁴ = 81622027 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81638419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40819205 + 40819206.

It is an arithmetic number, because the mean of its divisors is an integer number (40819206).

Almost surely, 2^81638411 is an apocalyptic number.

81638411 is a deficient number, since it is larger than the sum of its proper divisors (1).

81638411 is an equidigital number, since it uses as much as digits as its factorization.

81638411 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 32.

The square root of 81638411 is about 9035.3976669541. The cubic root of 81638411 is about 433.8086236017.

The spelling of 81638411 in words is "eighty-one million, six hundred thirty-eight thousand, four hundred eleven".