21820523 has 2 divisors, whose sum is σ = 21820524. Its totient is φ = 21820522.

The previous prime is 21820517. The next prime is 21820529. The reversal of 21820523 is 32502812.

It is a balanced prime because it is at equal distance from previous prime (21820517) and next prime (21820529).

It is a cyclic number.

It is not a de Polignac number, because 21820523 - 2⁶ = 21820459 is a prime.

It is a super-2 number, since 2×21820523² = 952270447987058, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21820529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10910261 + 10910262.

It is an arithmetic number, because the mean of its divisors is an integer number (10910262).

Almost surely, 2^21820523 is an apocalyptic number.

21820523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21820523 is an equidigital number, since it uses as much as digits as its factorization.

21820523 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21820523 is about 4671.2442667880. The cubic root of 21820523 is about 279.4398794144.

The spelling of 21820523 in words is "twenty-one million, eight hundred twenty thousand, five hundred twenty-three".