21525641 has 2 divisors, whose sum is σ = 21525642. Its totient is φ = 21525640.

The previous prime is 21525571. The next prime is 21525643. The reversal of 21525641 is 14652512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14661241 + 6864400 = 3829^2 + 2620^2 .

It is a cyclic number.

It is not a de Polignac number, because 21525641 - 2¹⁸ = 21263497 is a prime.

Together with 21525643, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21525641.

It is not a weakly prime, because it can be changed into another prime (21525643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10762820 + 10762821.

It is an arithmetic number, because the mean of its divisors is an integer number (10762821).

Almost surely, 2^21525641 is an apocalyptic number.

It is an amenable number.

21525641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21525641 is an equidigital number, since it uses as much as digits as its factorization.

21525641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2400, while the sum is 26.

The square root of 21525641 is about 4639.5733640067. The cubic root of 21525641 is about 278.1753849045.

The spelling of 21525641 in words is "twenty-one million, five hundred twenty-five thousand, six hundred forty-one".