21519523 has 2 divisors, whose sum is σ = 21519524. Its totient is φ = 21519522.

The previous prime is 21519517. The next prime is 21519539. The reversal of 21519523 is 32591512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21519523 - 2¹³ = 21511331 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21519491 and 21519500.

It is not a weakly prime, because it can be changed into another prime (21519583) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759761 + 10759762.

It is an arithmetic number, because the mean of its divisors is an integer number (10759762).

Almost surely, 2^21519523 is an apocalyptic number.

21519523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21519523 is an equidigital number, since it uses as much as digits as its factorization.

21519523 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2700, while the sum is 28.

The square root of 21519523 is about 4638.9139892867. The cubic root of 21519523 is about 278.1490281475.

The spelling of 21519523 in words is "twenty-one million, five hundred nineteen thousand, five hundred twenty-three".