21730693 has 2 divisors, whose sum is σ = 21730694. Its totient is φ = 21730692.

The previous prime is 21730663. The next prime is 21730727. The reversal of 21730693 is 39603712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13704804 + 8025889 = 3702^2 + 2833^2 .

It is a cyclic number.

It is not a de Polignac number, because 21730693 - 2¹⁷ = 21599621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21730663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865346 + 10865347.

It is an arithmetic number, because the mean of its divisors is an integer number (10865347).

Almost surely, 2^21730693 is an apocalyptic number.

It is an amenable number.

21730693 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730693 is an equidigital number, since it uses as much as digits as its factorization.

21730693 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 31.

The square root of 21730693 is about 4661.6191393120. The cubic root of 21730693 is about 279.0558890789.

The spelling of 21730693 in words is "twenty-one million, seven hundred thirty thousand, six hundred ninety-three".