21611893 has 2 divisors, whose sum is σ = 21611894. Its totient is φ = 21611892.

The previous prime is 21611857. The next prime is 21611897. The reversal of 21611893 is 39811612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14311089 + 7300804 = 3783^2 + 2702^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611893 - 2¹⁷ = 21480821 is a prime.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21611897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805946 + 10805947.

It is an arithmetic number, because the mean of its divisors is an integer number (10805947).

Almost surely, 2^21611893 is an apocalyptic number.

It is an amenable number.

21611893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21611893 is an equidigital number, since it uses as much as digits as its factorization.

21611893 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 31.

The square root of 21611893 is about 4648.8593224575. The cubic root of 21611893 is about 278.5464339867.

The spelling of 21611893 in words is "twenty-one million, six hundred eleven thousand, eight hundred ninety-three".