21121526417 has 4 divisors (see below), whose sum is σ = 21182046900. Its totient is φ = 21061005936.

The previous prime is 21121526411. The next prime is 21121526429. The reversal of 21121526417 is 71462512112.

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 18110699776 + 3010826641 = 134576^2 + 54871^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121526417 - 2¹⁸ = 21121264273 is a prime.

It is a super-2 number, since 2×21121526417² (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 (21121526411) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30259718 + ... + 30260415.

It is an arithmetic number, because the mean of its divisors is an integer number (5295511725).

Almost surely, 2^21121526417 is an apocalyptic number.

It is an amenable number.

21121526417 is a deficient number, since it is larger than the sum of its proper divisors (60520483).

21121526417 is an equidigital number, since it uses as much as digits as its factorization.

21121526417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60520482.

The product of its digits is 6720, while the sum is 32.

The spelling of 21121526417 in words is "twenty-one billion, one hundred twenty-one million, five hundred twenty-six thousand, four hundred seventeen".