21090529 has 2 divisors, whose sum is σ = 21090530. Its totient is φ = 21090528.

The previous prime is 21090497. The next prime is 21090533. The reversal of 21090529 is 92509012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18045504 + 3045025 = 4248^2 + 1745^2 .

It is a cyclic number.

It is not a de Polignac number, because 21090529 - 2⁵ = 21090497 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21090497 and 21090506.

It is not a weakly prime, because it can be changed into another prime (21094529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10545264 + 10545265.

It is an arithmetic number, because the mean of its divisors is an integer number (10545265).

Almost surely, 2^21090529 is an apocalyptic number.

It is an amenable number.

21090529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21090529 is an equidigital number, since it uses as much as digits as its factorization.

21090529 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 21090529 is about 4592.4425962662. The cubic root of 21090529 is about 276.2882979601.

The spelling of 21090529 in words is "twenty-one million, ninety thousand, five hundred twenty-nine".