21164111655 has 16 divisors (see below), whose sum is σ = 33988468320. Its totient is φ = 11245563008.

The previous prime is 21164111611. The next prime is 21164111671. The reversal of 21164111655 is 55611146112.

It is a cyclic number.

It is not a de Polignac number, because 21164111655 - 2²⁶ = 21097002791 is a prime.

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, 2618532 + ... + 2626601.

It is an arithmetic number, because the mean of its divisors is an integer number (2124279270).

Almost surely, 2^21164111655 is an apocalyptic number.

21164111655 is a deficient number, since it is larger than the sum of its proper divisors (12824356665).

21164111655 is a wasteful number, since it uses less digits than its factorization.

21164111655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5245410.

The product of its digits is 7200, while the sum is 33.

Adding to 21164111655 its reverse (55611146112), we get a palindrome (76775257767).

The spelling of 21164111655 in words is "twenty-one billion, one hundred sixty-four million, one hundred eleven thousand, six hundred fifty-five".