1945045681 has 4 divisors (see below), whose sum is σ = 1949666164. Its totient is φ = 1940425200.

The previous prime is 1945045673. The next prime is 1945045721. The reversal of 1945045681 is 1865405491.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 606144400 + 1338901281 = 24620^2 + 36591^2 .

It is a cyclic number.

It is not a de Polignac number, because 1945045681 - 2³ = 1945045673 is a prime.

It is a super-2 number, since 2×1945045681² = 7566405402353507522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1945045481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2309610 + ... + 2310451.

It is an arithmetic number, because the mean of its divisors is an integer number (487416541).

Almost surely, 2^1945045681 is an apocalyptic number.

It is an amenable number.

1945045681 is a deficient number, since it is larger than the sum of its proper divisors (4620483).

1945045681 is an equidigital number, since it uses as much as digits as its factorization.

1945045681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4620482.

The product of its (nonzero) digits is 172800, while the sum is 43.

The square root of 1945045681 is about 44102.6720392314. The cubic root of 1945045681 is about 1248.2740298652.

The spelling of 1945045681 in words is "one billion, nine hundred forty-five million, forty-five thousand, six hundred eighty-one".