21555660719 has 4 divisors (see below), whose sum is σ = 21599923344. Its totient is φ = 21511398096.

The previous prime is 21555660701. The next prime is 21555660727. The reversal of 21555660719 is 91706655512.

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 21555660719 - 2¹⁶ = 21555595183 is a prime.

It is a super-2 number, since 2×21555660719² (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 (21555660739) 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 3 ways as a sum of consecutive naturals, for example, 22130582 + ... + 22131555.

It is an arithmetic number, because the mean of its divisors is an integer number (5399980836).

Almost surely, 2^21555660719 is an apocalyptic number.

21555660719 is a deficient number, since it is larger than the sum of its proper divisors (44262625).

21555660719 is an equidigital number, since it uses as much as digits as its factorization.

21555660719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44262624.

The product of its (nonzero) digits is 567000, while the sum is 47.

The spelling of 21555660719 in words is "twenty-one billion, five hundred fifty-five million, six hundred sixty thousand, seven hundred nineteen".