81987201 has 16 divisors (see below), whose sum is σ = 121756800. Its totient is φ = 54525744.

The previous prime is 81987187. The next prime is 81987211. The reversal of 81987201 is 10278918.

It is not a de Polignac number, because 81987201 - 2⁶ = 81987137 is a prime.

It is a super-2 number, since 2×81987201² = 13443802255628802, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81987211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8395 + ... + 15311.

It is an arithmetic number, because the mean of its divisors is an integer number (7609800).

Almost surely, 2^81987201 is an apocalyptic number.

It is an amenable number.

81987201 is a deficient number, since it is larger than the sum of its proper divisors (39769599).

81987201 is a wasteful number, since it uses less digits than its factorization.

81987201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7365 (or 7359 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 81987201 is about 9054.6784040075. The cubic root of 81987201 is about 434.4255437347.

The spelling of 81987201 in words is "eighty-one million, nine hundred eighty-seven thousand, two hundred one".