81554040 has 80 divisors (see below), whose sum is σ = 274123080. Its totient is φ = 21746880.

The previous prime is 81554029. The next prime is 81554041. The reversal of 81554040 is 4045518.

81554040 is a `hidden beast` number, since 81 + 5 + 540 + 40 = 666.

It is a super-2 number, since 2×81554040² = 13302122880643200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 81553995 and 81554013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81554041) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9346 + ... + 15825.

Almost surely, 2^81554040 is an apocalyptic number.

It is an amenable number.

81554040 is an abundant number, since it is smaller than the sum of its proper divisors (192569040).

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

81554040 is a wasteful number, since it uses less digits than its factorization.

81554040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25194 (or 25181 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 81554040 is about 9030.7275454417. The cubic root of 81554040 is about 433.6591290895.

Adding to 81554040 its reverse (4045518), we get a palindrome (85599558).

The spelling of 81554040 in words is "eighty-one million, five hundred fifty-four thousand, forty".