20399540641 has 4 divisors (see below), whose sum is σ = 20586692500. Its totient is φ = 20212388784.

The previous prime is 20399540633. The next prime is 20399540659. The reversal of 20399540641 is 14604599302.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14604599302 = 2 ⋅7302299651.

It can be written as a sum of positive squares in 2 ways, for example, as 10638891025 + 9760649616 = 103145^2 + 98796^2 .

It is a cyclic number.

It is not a de Polignac number, because 20399540641 - 2³ = 20399540633 is a prime.

It is a super-2 number, since 2×20399540641² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20399540621) 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, 93575766 + ... + 93575983.

It is an arithmetic number, because the mean of its divisors is an integer number (5146673125).

Almost surely, 2^20399540641 is an apocalyptic number.

It is an amenable number.

20399540641 is a deficient number, since it is larger than the sum of its proper divisors (187151859).

20399540641 is a wasteful number, since it uses less digits than its factorization.

20399540641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187151858.

The product of its (nonzero) digits is 233280, while the sum is 43.

The spelling of 20399540641 in words is "twenty billion, three hundred ninety-nine million, five hundred forty thousand, six hundred forty-one".