81872447 has 2 divisors, whose sum is σ = 81872448. Its totient is φ = 81872446.

The previous prime is 81872437. The next prime is 81872467. The reversal of 81872447 is 74427818.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81872447 - 2⁶ = 81872383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81872437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40936223 + 40936224.

It is an arithmetic number, because the mean of its divisors is an integer number (40936224).

Almost surely, 2^81872447 is an apocalyptic number.

81872447 is a deficient number, since it is larger than the sum of its proper divisors (1).

81872447 is an equidigital number, since it uses as much as digits as its factorization.

81872447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100352, while the sum is 41.

The square root of 81872447 is about 9048.3394609177. The cubic root of 81872447 is about 434.2227667770. Note that the first 3 decimals are identical.

The spelling of 81872447 in words is "eighty-one million, eight hundred seventy-two thousand, four hundred forty-seven".