21903964991 has 2 divisors, whose sum is σ = 21903964992. Its totient is φ = 21903964990.

The previous prime is 21903964987. The next prime is 21903965003. The reversal of 21903964991 is 19946930912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21903964991 - 2² = 21903964987 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21903964931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10951982495 + 10951982496.

It is an arithmetic number, because the mean of its divisors is an integer number (10951982496).

Almost surely, 2^21903964991 is an apocalyptic number.

21903964991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21903964991 is an equidigital number, since it uses as much as digits as its factorization.

21903964991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 944784, while the sum is 53.

The spelling of 21903964991 in words is "twenty-one billion, nine hundred three million, nine hundred sixty-four thousand, nine hundred ninety-one".