81000436 has 48 divisors (see below), whose sum is σ = 159239808. Its totient is φ = 35740800.

The previous prime is 81000431. The next prime is 81000449. The reversal of 81000436 is 63400018.

It is a super-2 number, since 2×81000436² = 13122141264380192, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81000431) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 276306 + ... + 276598.

It is an arithmetic number, because the mean of its divisors is an integer number (3317496).

Almost surely, 2^81000436 is an apocalyptic number.

It is an amenable number.

81000436 is a deficient number, since it is larger than the sum of its proper divisors (78239372).

81000436 is a wasteful number, since it uses less digits than its factorization.

81000436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472 (or 470 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 81000436 is about 9000.0242221896. The cubic root of 81000436 is about 432.6756474128.

The spelling of 81000436 in words is "eighty-one million, four hundred thirty-six", and thus it is an aban number.