21851417519 has 4 divisors (see below), whose sum is σ = 22316341344. Its totient is φ = 21386493696.

The previous prime is 21851417509. The next prime is 21851417537. The reversal of 21851417519 is 91571415812.

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 21851417519 - 2⁴ = 21851417503 is a prime.

It is a super-2 number, since 2×21851417519² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21851417519.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851417509) 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, 232461842 + ... + 232461935.

It is an arithmetic number, because the mean of its divisors is an integer number (5579085336).

Almost surely, 2^21851417519 is an apocalyptic number.

21851417519 is a deficient number, since it is larger than the sum of its proper divisors (464923825).

21851417519 is an equidigital number, since it uses as much as digits as its factorization.

21851417519 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464923824.

The product of its digits is 100800, while the sum is 44.

The spelling of 21851417519 in words is "twenty-one billion, eight hundred fifty-one million, four hundred seventeen thousand, five hundred nineteen".