21653893 has 2 divisors, whose sum is σ = 21653894. Its totient is φ = 21653892.

The previous prime is 21653783. The next prime is 21653899. The reversal of 21653893 is 39835612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12124324 + 9529569 = 3482^2 + 3087^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653893 - 2²¹ = 19556741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21653899) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10826946 + 10826947.

It is an arithmetic number, because the mean of its divisors is an integer number (10826947).

Almost surely, 2^21653893 is an apocalyptic number.

It is an amenable number.

21653893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21653893 is an equidigital number, since it uses as much as digits as its factorization.

21653893 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 37.

The square root of 21653893 is about 4653.3743670588. The cubic root of 21653893 is about 278.7267572300.

The spelling of 21653893 in words is "twenty-one million, six hundred fifty-three thousand, eight hundred ninety-three".