20665400645 has 8 divisors (see below), whose sum is σ = 24799412256. Its totient is φ = 16531699536.

The previous prime is 20665400537. The next prime is 20665400647. The reversal of 20665400645 is 54600456602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20665400645 - 2¹⁶ = 20665335109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20665400599 and 20665400608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665400647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110054 + ... + 231176.

It is an arithmetic number, because the mean of its divisors is an integer number (3099926532).

Almost surely, 2^20665400645 is an apocalyptic number.

It is an amenable number.

20665400645 is a deficient number, since it is larger than the sum of its proper divisors (4134011611).

20665400645 is a wasteful number, since it uses less digits than its factorization.

20665400645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155251.

The product of its (nonzero) digits is 172800, while the sum is 38.

The spelling of 20665400645 in words is "twenty billion, six hundred sixty-five million, four hundred thousand, six hundred forty-five".