21621143365 has 16 divisors (see below), whose sum is σ = 26075831040. Its totient is φ = 17210065600.

The previous prime is 21621143351. The next prime is 21621143377. The reversal of 21621143365 is 56334112612.

It is not a de Polignac number, because 21621143365 - 2⁵ = 21621143333 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21621143365.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1547742 + ... + 1561648.

It is an arithmetic number, because the mean of its divisors is an integer number (1629739440).

Almost surely, 2^21621143365 is an apocalyptic number.

It is an amenable number.

21621143365 is a deficient number, since it is larger than the sum of its proper divisors (4454687675).

21621143365 is a wasteful number, since it uses less digits than its factorization.

21621143365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15452.

The product of its digits is 25920, while the sum is 34.

Adding to 21621143365 its reverse (56334112612), we get a palindrome (77955255977).

The spelling of 21621143365 in words is "twenty-one billion, six hundred twenty-one million, one hundred forty-three thousand, three hundred sixty-five".