81421420 has 12 divisors (see below), whose sum is σ = 170985024. Its totient is φ = 32568560.

The previous prime is 81421411. The next prime is 81421421. The reversal of 81421420 is 2412418.

It is a junction number, because it is equal to n+sod(n) for n = 81421391 and 81421400.

It is not an unprimeable number, because it can be changed into a prime (81421421) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 2035516 + ... + 2035555.

It is an arithmetic number, because the mean of its divisors is an integer number (14248752).

Almost surely, 2^81421420 is an apocalyptic number.

It is an amenable number.

81421420 is an abundant number, since it is smaller than the sum of its proper divisors (89563604).

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

81421420 is a wasteful number, since it uses less digits than its factorization.

81421420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4071080 (or 4071078 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 81421420 is about 9023.3818493955. The cubic root of 81421420 is about 433.4239350332.

Adding to 81421420 its reverse (2412418), we get a palindrome (83833838).

The spelling of 81421420 in words is "eighty-one million, four hundred twenty-one thousand, four hundred twenty".