81439606 has 4 divisors (see below), whose sum is σ = 122159412. Its totient is φ = 40719802.

The previous prime is 81439601. The next prime is 81439609. The reversal of 81439606 is 60693418.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81439601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20359900 + ... + 20359903.

It is an arithmetic number, because the mean of its divisors is an integer number (30539853).

Almost surely, 2^81439606 is an apocalyptic number.

81439606 is a deficient number, since it is larger than the sum of its proper divisors (40719806).

81439606 is a wasteful number, since it uses less digits than its factorization.

81439606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40719805.

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 81439606 is about 9024.3895084377. The cubic root of 81439606 is about 433.4562019760.

The spelling of 81439606 in words is "eighty-one million, four hundred thirty-nine thousand, six hundred six".