21164121 has 24 divisors (see below), whose sum is σ = 33505056. Its totient is φ = 12767040.

The previous prime is 21164107. The next prime is 21164141. The reversal of 21164121 is 12146112.

21164121 is a `hidden beast` number, since 2 + 1 + 1 + 641 + 21 = 666.

It is not a de Polignac number, because 21164121 - 2⁶ = 21164057 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21164094 and 21164103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30646 + ... + 31328.

It is an arithmetic number, because the mean of its divisors is an integer number (1396044).

Almost surely, 2^21164121 is an apocalyptic number.

It is an amenable number.

21164121 is a deficient number, since it is larger than the sum of its proper divisors (12340935).

21164121 is a wasteful number, since it uses less digits than its factorization.

21164121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1013 (or 1010 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 21164121 is about 4600.4479129754. The cubic root of 21164121 is about 276.6092793991.

Subtracting from 21164121 its reverse (12146112), we obtain a square (9018009 = 3003²).

The spelling of 21164121 in words is "twenty-one million, one hundred sixty-four thousand, one hundred twenty-one".