81421704 has 288 divisors, whose sum is σ = 295014720. Its totient is φ = 19740672.

The previous prime is 81421699. The next prime is 81421723. The reversal of 81421704 is 40712418.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1893507 + ... + 1893549.

Almost surely, 2^81421704 is an apocalyptic number.

81421704 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81421704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147507360).

81421704 is an abundant number, since it is smaller than the sum of its proper divisors (213593016).

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

81421704 is a wasteful number, since it uses less digits than its factorization.

81421704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109 (or 85 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 81421704 is about 9023.3975862754. The cubic root of 81421704 is about 433.4244389639.

The spelling of 81421704 in words is "eighty-one million, four hundred twenty-one thousand, seven hundred four".