20665210251601 has 4 divisors (see below), whose sum is σ = 20676774444912. Its totient is φ = 20653646058292.

The previous prime is 20665210251583. The next prime is 20665210251643. The reversal of 20665210251601 is 10615201256602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20665210251601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20665210255601) 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, 5782093975 + ... + 5782097548.

It is an arithmetic number, because the mean of its divisors is an integer number (5169193611228).

Almost surely, 2^{20665210251601} is an apocalyptic number.

It is an amenable number.

20665210251601 is a deficient number, since it is larger than the sum of its proper divisors (11564193311).

20665210251601 is a wasteful number, since it uses less digits than its factorization.

20665210251601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11564193310.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 20665210251601 in words is "twenty trillion, six hundred sixty-five billion, two hundred ten million, two hundred fifty-one thousand, six hundred one".