21063517457 has 4 divisors (see below), whose sum is σ = 21063855540. Its totient is φ = 21063179376.

The previous prime is 21063517451. The next prime is 21063517493. The reversal of 21063517457 is 75471536012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18729564736 + 2333952721 = 136856^2 + 48311^2 .

It is a cyclic number.

It is not a de Polignac number, because 21063517457 - 2⁴ = 21063517441 is a prime.

It is a super-2 number, since 2×21063517457² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21063517451) 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 in 3 ways as a sum of consecutive naturals, for example, 45482 + ... + 210227.

It is an arithmetic number, because the mean of its divisors is an integer number (5265963885).

Almost surely, 2^21063517457 is an apocalyptic number.

It is an amenable number.

21063517457 is a deficient number, since it is larger than the sum of its proper divisors (338083).

21063517457 is an equidigital number, since it uses as much as digits as its factorization.

21063517457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338082.

The product of its (nonzero) digits is 176400, while the sum is 41.

The spelling of 21063517457 in words is "twenty-one billion, sixty-three million, five hundred seventeen thousand, four hundred fifty-seven".