20591903977 has 4 divisors (see below), whose sum is σ = 21256158976. Its totient is φ = 19927648980.

The previous prime is 20591903953. The next prime is 20591903989. The reversal of 20591903977 is 77930919502.

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, and also an emirpimes, since its reverse is a distinct semiprime: 77930919502 = 2 ⋅38965459751.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20591903977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20591903947) 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 3 ways as a sum of consecutive naturals, for example, 332127453 + ... + 332127514.

It is an arithmetic number, because the mean of its divisors is an integer number (5314039744).

Almost surely, 2^20591903977 is an apocalyptic number.

It is an amenable number.

20591903977 is a deficient number, since it is larger than the sum of its proper divisors (664254999).

20591903977 is an equidigital number, since it uses as much as digits as its factorization.

20591903977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 664254998.

The product of its (nonzero) digits is 1071630, while the sum is 52.

The spelling of 20591903977 in words is "twenty billion, five hundred ninety-one million, nine hundred three thousand, nine hundred seventy-seven".