21873609391 has 2 divisors, whose sum is σ = 21873609392. Its totient is φ = 21873609390.

The previous prime is 21873609379. The next prime is 21873609409. The reversal of 21873609391 is 19390637812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21873609391 - 2²¹ = 21871512239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21873609301) 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, 10936804695 + 10936804696.

It is an arithmetic number, because the mean of its divisors is an integer number (10936804696).

Almost surely, 2^21873609391 is an apocalyptic number.

21873609391 is a deficient number, since it is larger than the sum of its proper divisors (1).

21873609391 is an equidigital number, since it uses as much as digits as its factorization.

21873609391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 489888, while the sum is 49.

The spelling of 21873609391 in words is "twenty-one billion, eight hundred seventy-three million, six hundred nine thousand, three hundred ninety-one".