21495299517 has 24 divisors (see below), whose sum is σ = 32489607384. Its totient is φ = 13679812224.

The previous prime is 21495299509. The next prime is 21495299519. The reversal of 21495299517 is 71599259412.

It is a happy number.

21495299517 is a `hidden beast` number, since 2 + 14 + 9 + 529 + 95 + 17 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 4654787076 + 16840512441 = 68226^2 + 129771^2 .

It is not a de Polignac number, because 21495299517 - 2³ = 21495299509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21495299519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 591318 + ... + 626615.

It is an arithmetic number, because the mean of its divisors is an integer number (1353733641).

Almost surely, 2^21495299517 is an apocalyptic number.

It is an amenable number.

21495299517 is a deficient number, since it is larger than the sum of its proper divisors (10994307867).

21495299517 is a wasteful number, since it uses less digits than its factorization.

21495299517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1218029 (or 1218026 counting only the distinct ones).

The product of its digits is 2041200, while the sum is 54.

The spelling of 21495299517 in words is "twenty-one billion, four hundred ninety-five million, two hundred ninety-nine thousand, five hundred seventeen".