81206643 has 8 divisors (see below), whose sum is σ = 123743488. Its totient is φ = 46403784.

The previous prime is 81206633. The next prime is 81206663. The reversal of 81206643 is 34660218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81206643 - 2⁶ = 81206579 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81206643.

It is not an unprimeable number, because it can be changed into a prime (81206623) 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, 1933471 + ... + 1933512.

It is an arithmetic number, because the mean of its divisors is an integer number (15467936).

Almost surely, 2^81206643 is an apocalyptic number.

81206643 is a deficient number, since it is larger than the sum of its proper divisors (42536845).

81206643 is a wasteful number, since it uses less digits than its factorization.

81206643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3866993.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 81206643 is about 9011.4728540899. The cubic root of 81206643 is about 433.0424978778.

The spelling of 81206643 in words is "eighty-one million, two hundred six thousand, six hundred forty-three".