21115430775 has 18 divisors (see below), whose sum is σ = 37820083080. Its totient is φ = 11261562960.

The previous prime is 21115430753. The next prime is 21115430779. The reversal of 21115430775 is 57703451112.

21115430775 is a `hidden beast` number, since 211 + 1 + 5 + 430 + 7 + 7 + 5 = 666.

It is not a de Polignac number, because 21115430775 - 2⁸ = 21115430519 is a prime.

It is a super-2 number, since 2×21115430775² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115430779) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 46922955 + ... + 46923404.

Almost surely, 2^21115430775 is an apocalyptic number.

21115430775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21115430775 is a deficient number, since it is larger than the sum of its proper divisors (16704652305).

21115430775 is a wasteful number, since it uses less digits than its factorization.

21115430775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93846375 (or 93846367 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 36.

Adding to 21115430775 its reverse (57703451112), we get a palindrome (78818881887).

The spelling of 21115430775 in words is "twenty-one billion, one hundred fifteen million, four hundred thirty thousand, seven hundred seventy-five".