21933521 has 2 divisors, whose sum is σ = 21933522. Its totient is φ = 21933520.

The previous prime is 21933517. The next prime is 21933529. The reversal of 21933521 is 12533912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21752896 + 180625 = 4664^2 + 425^2 .

It is a cyclic number.

It is not a de Polignac number, because 21933521 - 2² = 21933517 is a prime.

It is not a weakly prime, because it can be changed into another prime (21933529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10966760 + 10966761.

It is an arithmetic number, because the mean of its divisors is an integer number (10966761).

Almost surely, 2^21933521 is an apocalyptic number.

It is an amenable number.

21933521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21933521 is an equidigital number, since it uses as much as digits as its factorization.

21933521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 26.

The square root of 21933521 is about 4683.3237129201. The cubic root of 21933521 is about 279.9214107671.

The spelling of 21933521 in words is "twenty-one million, nine hundred thirty-three thousand, five hundred twenty-one".