81820422 has 64 divisors (see below), whose sum is σ = 202694400. Its totient is φ = 24312960.

The previous prime is 81820421. The next prime is 81820423. The reversal of 81820422 is 22402818.

It is an interprime number because it is at equal distance from previous prime (81820421) and next prime (81820423).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81820421) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15097 + ... + 19787.

It is an arithmetic number, because the mean of its divisors is an integer number (3167100).

Almost surely, 2^81820422 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81820422, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101347200).

81820422 is an abundant number, since it is smaller than the sum of its proper divisors (120873978).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81820422 is a wasteful number, since it uses less digits than its factorization.

81820422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4738 (or 4732 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 81820422 is about 9045.4641671945. The cubic root of 81820422 is about 434.1307731662.

The spelling of 81820422 in words is "eighty-one million, eight hundred twenty thousand, four hundred twenty-two".