81620039 has 4 divisors (see below), whose sum is σ = 83826024. Its totient is φ = 79414056.

The previous prime is 81620027. The next prime is 81620041. The reversal of 81620039 is 93002618.

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

It is a cyclic number.

It is not a de Polignac number, because 81620039 - 2¹² = 81615943 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81619993 and 81620020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81620639) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1102937 + ... + 1103010.

It is an arithmetic number, because the mean of its divisors is an integer number (20956506).

Almost surely, 2^81620039 is an apocalyptic number.

81620039 is a deficient number, since it is larger than the sum of its proper divisors (2205985).

81620039 is a wasteful number, since it uses less digits than its factorization.

81620039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2205984.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 81620039 is about 9034.3809417137. The cubic root of 81620039 is about 433.7760795665.

The spelling of 81620039 in words is "eighty-one million, six hundred twenty thousand, thirty-nine".