81405366 has 48 divisors (see below), whose sum is σ = 192037104. Its totient is φ = 22934016.

The previous prime is 81405361. The next prime is 81405391. The reversal of 81405366 is 66350418.

It is a super-2 number, since 2×81405366² = 13253667227187912, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81405361) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19566 + ... + 23358.

It is an arithmetic number, because the mean of its divisors is an integer number (4000773).

Almost surely, 2^81405366 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81405366, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96018552).

81405366 is an abundant number, since it is smaller than the sum of its proper divisors (110631738).

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

81405366 is a wasteful number, since it uses less digits than its factorization.

81405366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3885 (or 3878 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 81405366 is about 9022.4922277606. The cubic root of 81405366 is about 433.3954468491.

The spelling of 81405366 in words is "eighty-one million, four hundred five thousand, three hundred sixty-six".