81617340 has 288 divisors, whose sum is σ = 297851904. Its totient is φ = 16558080.

The previous prime is 81617321. The next prime is 81617381. The reversal of 81617340 is 4371618.

It is a happy number.

It is a super-2 number, since 2×81617340² = 13322780377351200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 81617298 and 81617307.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1149505 + ... + 1149575.

It is an arithmetic number, because the mean of its divisors is an integer number (1034208).

Almost surely, 2^81617340 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81617340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148925952).

81617340 is an abundant number, since it is smaller than the sum of its proper divisors (216234564).

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

81617340 is a wasteful number, since it uses less digits than its factorization.

81617340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 81617340 is about 9034.2315666580. The cubic root of 81617340 is about 433.7712981649.

Adding to 81617340 its reverse (4371618), we get a palindrome (85988958).

The spelling of 81617340 in words is "eighty-one million, six hundred seventeen thousand, three hundred forty".