21164929 has 2 divisors, whose sum is σ = 21164930. Its totient is φ = 21164928.

The previous prime is 21164863. The next prime is 21164939. The reversal of 21164929 is 92946112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19847025 + 1317904 = 4455^2 + 1148^2 .

It is a cyclic number.

It is not a de Polignac number, because 21164929 - 2²¹ = 19067777 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21164894 and 21164903.

It is not a weakly prime, because it can be changed into another prime (21164939) 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 as a sum of consecutive naturals, namely, 10582464 + 10582465.

It is an arithmetic number, because the mean of its divisors is an integer number (10582465).

Almost surely, 2^21164929 is an apocalyptic number.

It is an amenable number.

21164929 is a deficient number, since it is larger than the sum of its proper divisors (1).

21164929 is an equidigital number, since it uses as much as digits as its factorization.

21164929 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 21164929 is about 4600.5357296732. The cubic root of 21164929 is about 276.6127994674.

The spelling of 21164929 in words is "twenty-one million, one hundred sixty-four thousand, nine hundred twenty-nine".