20666580401 has 4 divisors (see below), whose sum is σ = 20685914100. Its totient is φ = 20647246704.

The previous prime is 20666580391. The next prime is 20666580409. The reversal of 20666580401 is 10408566602.

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 12734896801 + 7931683600 = 112849^2 + 89060^2 .

It is a cyclic number.

It is not a de Polignac number, because 20666580401 - 2²² = 20662386097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20666580409) 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, 9665246 + ... + 9667383.

It is an arithmetic number, because the mean of its divisors is an integer number (5171478525).

Almost surely, 2^20666580401 is an apocalyptic number.

It is an amenable number.

20666580401 is a deficient number, since it is larger than the sum of its proper divisors (19333699).

20666580401 is a wasteful number, since it uses less digits than its factorization.

20666580401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19333698.

The product of its (nonzero) digits is 69120, while the sum is 38.

The spelling of 20666580401 in words is "twenty billion, six hundred sixty-six million, five hundred eighty thousand, four hundred one".