20720671651 has 4 divisors (see below), whose sum is σ = 21435177600. Its totient is φ = 20006165704.

The previous prime is 20720671637. The next prime is 20720671691. The reversal of 20720671651 is 15617602702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20720671651 - 2⁵ = 20720671619 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20720671651.

It is not an unprimeable number, because it can be changed into a prime (20720671691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 357252931 + ... + 357252988.

It is an arithmetic number, because the mean of its divisors is an integer number (5358794400).

Almost surely, 2^20720671651 is an apocalyptic number.

20720671651 is a deficient number, since it is larger than the sum of its proper divisors (714505949).

20720671651 is an equidigital number, since it uses as much as digits as its factorization.

20720671651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714505948.

The product of its (nonzero) digits is 35280, while the sum is 37.

The spelling of 20720671651 in words is "twenty billion, seven hundred twenty million, six hundred seventy-one thousand, six hundred fifty-one".