81697750 has 64 divisors (see below), whose sum is σ = 165784320. Its totient is φ = 30028800.

The previous prime is 81697747. The next prime is 81697799. The reversal of 81697750 is 5779618.

It is a junction number, because it is equal to n+sod(n) for n = 81697697 and 81697706.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 199546 + ... + 199954.

It is an arithmetic number, because the mean of its divisors is an integer number (2590380).

Almost surely, 2^81697750 is an apocalyptic number.

81697750 is an abundant number, since it is smaller than the sum of its proper divisors (84086570).

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

81697750 is a wasteful number, since it uses less digits than its factorization.

81697750 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490 (or 480 counting only the distinct ones).

The product of its (nonzero) digits is 105840, while the sum is 43.

The square root of 81697750 is about 9038.6807665721. The cubic root of 81697750 is about 433.9137029604.

The spelling of 81697750 in words is "eighty-one million, six hundred ninety-seven thousand, seven hundred fifty".