21223693 has 2 divisors, whose sum is σ = 21223694. Its totient is φ = 21223692.

The previous prime is 21223673. The next prime is 21223711. The reversal of 21223693 is 39632212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 311364 = 4573^2 + 558^2 .

It is a cyclic number.

It is not a de Polignac number, because 21223693 - 2⁵ = 21223661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21223603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611846 + 10611847.

It is an arithmetic number, because the mean of its divisors is an integer number (10611847).

Almost surely, 2^21223693 is an apocalyptic number.

It is an amenable number.

21223693 is a deficient number, since it is larger than the sum of its proper divisors (1).

21223693 is an equidigital number, since it uses as much as digits as its factorization.

21223693 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 28.

The square root of 21223693 is about 4606.9179502136. The cubic root of 21223693 is about 276.8685661956.

The spelling of 21223693 in words is "twenty-one million, two hundred twenty-three thousand, six hundred ninety-three".