21356666519 has 4 divisors (see below), whose sum is σ = 21457883160. Its totient is φ = 21255449880.

The previous prime is 21356666503. The next prime is 21356666521. The reversal of 21356666519 is 91566665312.

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

It is a cyclic number.

It is not a de Polignac number, because 21356666519 - 2⁴ = 21356666503 is a prime.

It is a super-2 number, since 2×21356666519² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356666579) 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, 50608004 + ... + 50608425.

It is an arithmetic number, because the mean of its divisors is an integer number (5364470790).

Almost surely, 2^21356666519 is an apocalyptic number.

21356666519 is a deficient number, since it is larger than the sum of its proper divisors (101216641).

21356666519 is a wasteful number, since it uses less digits than its factorization.

21356666519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101216640.

The product of its digits is 1749600, while the sum is 50.

The spelling of 21356666519 in words is "twenty-one billion, three hundred fifty-six million, six hundred sixty-six thousand, five hundred nineteen".