81399648 has 96 divisors (see below), whose sum is σ = 245427840. Its totient is φ = 23362560.

The previous prime is 81399623. The next prime is 81399673. The reversal of 81399648 is 84699318.

It is an interprime number because it is at equal distance from previous prime (81399623) and next prime (81399673).

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 81399597 and 81399606.

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, 18036 + ... + 22092.

It is an arithmetic number, because the mean of its divisors is an integer number (2556540).

Almost surely, 2^81399648 is an apocalyptic number.

81399648 is a gapful number since it is divisible by the number (88) 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 81399648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122713920).

81399648 is an abundant number, since it is smaller than the sum of its proper divisors (164028192).

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

81399648 is a wasteful number, since it uses less digits than its factorization.

81399648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4100 (or 4092 counting only the distinct ones).

The product of its digits is 373248, while the sum is 48.

The square root of 81399648 is about 9022.1753474425. The cubic root of 81399648 is about 433.3852992249.

The spelling of 81399648 in words is "eighty-one million, three hundred ninety-nine thousand, six hundred forty-eight".