201820171536 has 75 divisors (see below), whose sum is σ = 584172941671. Its totient is φ = 67267999584.

The previous prime is 201820171499. The next prime is 201820171537. The reversal of 201820171536 is 635171028102.

The square root of 201820171536 is 449244.

It is a perfect power (a square), and thus also a powerful number.

201820171536 is a `hidden beast` number, since 20 + 18 + 20 + 1 + 71 + 536 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 201820171536.

It is not an unprimeable number, because it can be changed into a prime (201820171537) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 16166545 + ... + 16179023.

Almost surely, 2^201820171536 is an apocalyptic number.

201820171536 is the 449244-th square number.

It is an amenable number.

201820171536 is an abundant number, since it is smaller than the sum of its proper divisors (382352770135).

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

201820171536 is an frugal number, since it uses more digits than its factorization.

201820171536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24978 (or 12484 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

Multiplying 201820171536 by its sum of digits (36), we get a square (7265526175296 = 2695464²).

201820171536 divided by its sum of digits (36) gives a square (5606115876 = 74874²).

Adding to 201820171536 its reverse (635171028102), we get a palindrome (836991199638).

The spelling of 201820171536 in words is "two hundred one billion, eight hundred twenty million, one hundred seventy-one thousand, five hundred thirty-six".