21953963491 has 2 divisors, whose sum is σ = 21953963492. Its totient is φ = 21953963490.

The previous prime is 21953963461. The next prime is 21953963509. The reversal of 21953963491 is 19436935912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21953963491 - 2⁷ = 21953963363 is a prime.

It is not a weakly prime, because it can be changed into another prime (21953963401) 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, 10976981745 + 10976981746.

It is an arithmetic number, because the mean of its divisors is an integer number (10976981746).

Almost surely, 2^21953963491 is an apocalyptic number.

21953963491 is a deficient number, since it is larger than the sum of its proper divisors (1).

21953963491 is an equidigital number, since it uses as much as digits as its factorization.

21953963491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1574640, while the sum is 52.

The spelling of 21953963491 in words is "twenty-one billion, nine hundred fifty-three million, nine hundred sixty-three thousand, four hundred ninety-one".