81390447 has 8 divisors (see below), whose sum is σ = 120578480. Its totient is φ = 54260280.

The previous prime is 81390383. The next prime is 81390473. The reversal of 81390447 is 74409318.

It is a happy number.

It is not a de Polignac number, because 81390447 - 2⁶ = 81390383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390487) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1507204 + ... + 1507257.

It is an arithmetic number, because the mean of its divisors is an integer number (15072310).

Almost surely, 2^81390447 is an apocalyptic number.

81390447 is a deficient number, since it is larger than the sum of its proper divisors (39188033).

81390447 is a wasteful number, since it uses less digits than its factorization.

81390447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3014470 (or 3014464 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 81390447 is about 9021.6654227476. The cubic root of 81390447 is about 433.3689693902.

The spelling of 81390447 in words is "eighty-one million, three hundred ninety thousand, four hundred forty-seven".