81425220 has 48 divisors (see below), whose sum is σ = 235350528. Its totient is φ = 21012480.

The previous prime is 81425219. The next prime is 81425231. The reversal of 81425220 is 2252418.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20029 + ... + 23748.

It is an arithmetic number, because the mean of its divisors is an integer number (4903136).

Almost surely, 2^81425220 is an apocalyptic number.

It is an amenable number.

81425220 is an abundant number, since it is smaller than the sum of its proper divisors (153925308).

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

81425220 is a wasteful number, since it uses less digits than its factorization.

81425220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43820 (or 43818 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 81425220 is about 9023.5924110079. The cubic root of 81425220 is about 433.4306776706.

Adding to 81425220 its reverse (2252418), we get a palindrome (83677638).

The spelling of 81425220 in words is "eighty-one million, four hundred twenty-five thousand, two hundred twenty".