81400704 has 128 divisors (see below), whose sum is σ = 269671680. Its totient is φ = 21135360.

The previous prime is 81400681. The next prime is 81400717. The reversal of 81400704 is 40700418.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×81400704² = 13252149223391232, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28192 + ... + 30944.

It is an arithmetic number, because the mean of its divisors is an integer number (2106810).

Almost surely, 2^81400704 is an apocalyptic number.

81400704 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 81400704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (134835840).

81400704 is an abundant number, since it is smaller than the sum of its proper divisors (188270976).

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

81400704 is a wasteful number, since it uses less digits than its factorization.

81400704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2788 (or 2776 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 81400704 is about 9022.2338697243. The cubic root of 81400704 is about 433.3871733235.

The spelling of 81400704 in words is "eighty-one million, four hundred thousand, seven hundred four".