645220201536 has 63 divisors (see below), whose sum is σ = 1849462468581. Its totient is φ = 215066974464.

The previous prime is 645220201531. The next prime is 645220201547. The reversal of 645220201536 is 635102022546.

The square root of 645220201536 is 803256.

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

645220201536 is a `hidden beast` number, since 64 + 522 + 0 + 20 + 1 + 53 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 208352079936 + 436868121600 = 456456^2 + 660960^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 645220201536.

It is not an unprimeable number, because it can be changed into a prime (645220201531) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 19261410 + ... + 19294878.

Almost surely, 2^645220201536 is an apocalyptic number.

645220201536 is the 803256-th square number.

It is an amenable number.

645220201536 is an abundant number, since it is smaller than the sum of its proper divisors (1204242267045).

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

645220201536 is an frugal number, since it uses more digits than its factorization.

645220201536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66956 (or 33474 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

Multiplying 645220201536 by its sum of digits (36), we get a square (23227927255296 = 4819536²).

645220201536 divided by its sum of digits (36) gives a square (17922783376 = 133876²).

The spelling of 645220201536 in words is "six hundred forty-five billion, two hundred twenty million, two hundred one thousand, five hundred thirty-six".