81421438 has 24 divisors (see below), whose sum is σ = 146660544. Its totient is φ = 33768000.

The previous prime is 81421421. The next prime is 81421463. The reversal of 81421438 is 83412418.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10363 + ... + 16438.

It is an arithmetic number, because the mean of its divisors is an integer number (6110856).

Almost surely, 2^81421438 is an apocalyptic number.

81421438 is a deficient number, since it is larger than the sum of its proper divisors (65239106).

81421438 is a wasteful number, since it uses less digits than its factorization.

81421438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26848 (or 26841 counting only the distinct ones).

The product of its digits is 6144, while the sum is 31.

The square root of 81421438 is about 9023.3828468042. The cubic root of 81421438 is about 433.4239669725.

The spelling of 81421438 in words is "eighty-one million, four hundred twenty-one thousand, four hundred thirty-eight".