21072523 has 2 divisors, whose sum is σ = 21072524. Its totient is φ = 21072522.

The previous prime is 21072517. The next prime is 21072533. The reversal of 21072523 is 32527012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21072523 - 2⁹ = 21072011 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 = 21072494 and 21072503.

It is not a weakly prime, because it can be changed into another prime (21072533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10536261 + 10536262.

It is an arithmetic number, because the mean of its divisors is an integer number (10536262).

Almost surely, 2^21072523 is an apocalyptic number.

21072523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21072523 is an equidigital number, since it uses as much as digits as its factorization.

21072523 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21072523 is about 4590.4817829940. The cubic root of 21072523 is about 276.2096486997.

Adding to 21072523 its reverse (32527012), we get a palindrome (53599535).

The spelling of 21072523 in words is "twenty-one million, seventy-two thousand, five hundred twenty-three".