20766745991 has 4 divisors (see below), whose sum is σ = 20778355800. Its totient is φ = 20755136184.

The previous prime is 20766745949. The next prime is 20766746017. The reversal of 20766745991 is 19954766702.

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 20766745991 - 2⁶ = 20766745927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20766745091) 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, 5802221 + ... + 5805798.

It is an arithmetic number, because the mean of its divisors is an integer number (5194588950).

Almost surely, 2^20766745991 is an apocalyptic number.

20766745991 is a deficient number, since it is larger than the sum of its proper divisors (11609809).

20766745991 is a wasteful number, since it uses less digits than its factorization.

20766745991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11609808.

The product of its (nonzero) digits is 5715360, while the sum is 56.

The spelling of 20766745991 in words is "twenty billion, seven hundred sixty-six million, seven hundred forty-five thousand, nine hundred ninety-one".