20763991 has 2 divisors, whose sum is σ = 20763992. Its totient is φ = 20763990.

The previous prime is 20763983. The next prime is 20764039. The reversal of 20763991 is 19936702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20763991 - 2³ = 20763983 is a prime.

It is a super-2 number, since 2×20763991² = 862286644496162, which contains 22 as substring.

It is equal to p_1315999 and since 20763991 and 1315999 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20763991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20763931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10381995 + 10381996.

It is an arithmetic number, because the mean of its divisors is an integer number (10381996).

Almost surely, 2^20763991 is an apocalyptic number.

20763991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20763991 is an equidigital number, since it uses as much as digits as its factorization.

20763991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 20763991 is about 4556.7522425517. The cubic root of 20763991 is about 274.8549802874.

The spelling of 20763991 in words is "twenty million, seven hundred sixty-three thousand, nine hundred ninety-one".