81701520 has 240 divisors, whose sum is σ = 285731712. Its totient is φ = 19261440.

The previous prime is 81701519. The next prime is 81701531. The reversal of 81701520 is 2510718.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1992700 + ... + 1992740.

Almost surely, 2^81701520 is an apocalyptic number.

81701520 is a gapful number since it is divisible by the number (80) 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 81701520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142865856).

81701520 is an abundant number, since it is smaller than the sum of its proper divisors (204030192).

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

81701520 is a wasteful number, since it uses less digits than its factorization.

81701520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118 (or 93 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 81701520 is about 9038.8893122994. The cubic root of 81701520 is about 433.9203772751.

The spelling of 81701520 in words is "eighty-one million, seven hundred one thousand, five hundred twenty".