20645401399 has 4 divisors (see below), whose sum is σ = 23594744464. Its totient is φ = 17696058336.

The previous prime is 20645401379. The next prime is 20645401417. The reversal of 20645401399 is 99310454602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99310454602 = 2 ⋅49655227301.

It is a cyclic number.

It is not a de Polignac number, because 20645401399 - 2⁹ = 20645400887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20645401379) 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, 1474671522 + ... + 1474671535.

It is an arithmetic number, because the mean of its divisors is an integer number (5898686116).

Almost surely, 2^20645401399 is an apocalyptic number.

20645401399 is a deficient number, since it is larger than the sum of its proper divisors (2949343065).

20645401399 is an equidigital number, since it uses as much as digits as its factorization.

20645401399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2949343064.

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

The spelling of 20645401399 in words is "twenty billion, six hundred forty-five million, four hundred one thousand, three hundred ninety-nine".