21293861 has 2 divisors, whose sum is σ = 21293862. Its totient is φ = 21293860.

The previous prime is 21293803. The next prime is 21293887. The reversal of 21293861 is 16839212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20702500 + 591361 = 4550^2 + 769^2 .

It is a cyclic number.

It is not a de Polignac number, because 21293861 - 2¹⁰ = 21292837 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21293761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10646930 + 10646931.

It is an arithmetic number, because the mean of its divisors is an integer number (10646931).

Almost surely, 2^21293861 is an apocalyptic number.

It is an amenable number.

21293861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21293861 is an equidigital number, since it uses as much as digits as its factorization.

21293861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 21293861 is about 4614.5271697109. The cubic root of 21293861 is about 277.1733504625.

The spelling of 21293861 in words is "twenty-one million, two hundred ninety-three thousand, eight hundred sixty-one".