81413639 has 2 divisors, whose sum is σ = 81413640. Its totient is φ = 81413638.

The previous prime is 81413617. The next prime is 81413681. The reversal of 81413639 is 93631418.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81413639 - 2¹² = 81409543 is a prime.

It is a Chen prime.

It is equal to p_4747238 and since 81413639 and 4747238 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 81413599 and 81413608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81413609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40706819 + 40706820.

It is an arithmetic number, because the mean of its divisors is an integer number (40706820).

Almost surely, 2^81413639 is an apocalyptic number.

81413639 is a deficient number, since it is larger than the sum of its proper divisors (1).

81413639 is an equidigital number, since it uses as much as digits as its factorization.

81413639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 81413639 is about 9022.9506814567. The cubic root of 81413639 is about 433.4101279414.

The spelling of 81413639 in words is "eighty-one million, four hundred thirteen thousand, six hundred thirty-nine".