21969931523 has 2 divisors, whose sum is σ = 21969931524. Its totient is φ = 21969931522.

The previous prime is 21969931519. The next prime is 21969931537. The reversal of 21969931523 is 32513996912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21969931523 - 2² = 21969931519 is a prime.

It is a super-2 number, since 2×21969931523² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21969931573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10984965761 + 10984965762.

It is an arithmetic number, because the mean of its divisors is an integer number (10984965762).

Almost surely, 2^21969931523 is an apocalyptic number.

21969931523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21969931523 is an equidigital number, since it uses as much as digits as its factorization.

21969931523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 787320, while the sum is 50.

The spelling of 21969931523 in words is "twenty-one billion, nine hundred sixty-nine million, nine hundred thirty-one thousand, five hundred twenty-three".