21010525409 has 2 divisors, whose sum is σ = 21010525410. Its totient is φ = 21010525408.

The previous prime is 21010525387. The next prime is 21010525411. The reversal of 21010525409 is 90452501012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20209465600 + 801059809 = 142160^2 + 28303^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010525409 - 2³² = 16715558113 is a prime.

Together with 21010525411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21010525429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505262704 + 10505262705.

It is an arithmetic number, because the mean of its divisors is an integer number (10505262705).

Almost surely, 2^21010525409 is an apocalyptic number.

It is an amenable number.

21010525409 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010525409 is an equidigital number, since it uses as much as digits as its factorization.

21010525409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 29.

The spelling of 21010525409 in words is "twenty-one billion, ten million, five hundred twenty-five thousand, four hundred nine".