21240141991 has 2 divisors, whose sum is σ = 21240141992. Its totient is φ = 21240141990.

The previous prime is 21240141947. The next prime is 21240142037. The reversal of 21240141991 is 19914104212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21240141991 - 2¹⁹ = 21239617703 is a prime.

It is a super-2 number, since 2×21240141991² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21240141491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620070995 + 10620070996.

It is an arithmetic number, because the mean of its divisors is an integer number (10620070996).

Almost surely, 2^21240141991 is an apocalyptic number.

21240141991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240141991 is an equidigital number, since it uses as much as digits as its factorization.

21240141991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The spelling of 21240141991 in words is "twenty-one billion, two hundred forty million, one hundred forty-one thousand, nine hundred ninety-one".