21612021611 has 4 divisors (see below), whose sum is σ = 21612601800. Its totient is φ = 21611441424.

The previous prime is 21612021593. The next prime is 21612021623. The reversal of 21612021611 is 11612021612.

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 21612021611 - 2¹⁴ = 21612005227 is a prime.

It is a super-2 number, since 2×21612021611² (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 (21612021911) 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, 230081 + ... + 310098.

It is an arithmetic number, because the mean of its divisors is an integer number (5403150450).

Almost surely, 2^21612021611 is an apocalyptic number.

21612021611 is a deficient number, since it is larger than the sum of its proper divisors (580189).

21612021611 is an equidigital number, since it uses as much as digits as its factorization.

21612021611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 580188.

The product of its (nonzero) digits is 288, while the sum is 23.

Subtracting from 21612021611 its reverse (11612021612), we obtain a palindrome (9999999999).

The spelling of 21612021611 in words is "twenty-one billion, six hundred twelve million, twenty-one thousand, six hundred eleven".