21572533 has 2 divisors, whose sum is σ = 21572534. Its totient is φ = 21572532.

The previous prime is 21572531. The next prime is 21572539. The reversal of 21572533 is 33527512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 842724 = 4553^2 + 918^2 .

It is a cyclic number.

It is not a de Polignac number, because 21572533 - 2¹ = 21572531 is a prime.

Together with 21572531, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21572531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786266 + 10786267.

It is an arithmetic number, because the mean of its divisors is an integer number (10786267).

Almost surely, 2^21572533 is an apocalyptic number.

It is an amenable number.

21572533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21572533 is an equidigital number, since it uses as much as digits as its factorization.

21572533 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6300, while the sum is 28.

The square root of 21572533 is about 4644.6240967381. The cubic root of 21572533 is about 278.3772331663.

The spelling of 21572533 in words is "twenty-one million, five hundred seventy-two thousand, five hundred thirty-three".