21931801747 has 2 divisors, whose sum is σ = 21931801748. Its totient is φ = 21931801746.

The previous prime is 21931801693. The next prime is 21931801751. The reversal of 21931801747 is 74710813912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21931801747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21931808747) 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 as a sum of consecutive naturals, namely, 10965900873 + 10965900874.

It is an arithmetic number, because the mean of its divisors is an integer number (10965900874).

Almost surely, 2^21931801747 is an apocalyptic number.

21931801747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21931801747 is an equidigital number, since it uses as much as digits as its factorization.

21931801747 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84672, while the sum is 43.

The spelling of 21931801747 in words is "twenty-one billion, nine hundred thirty-one million, eight hundred one thousand, seven hundred forty-seven".