21545011 has 2 divisors, whose sum is σ = 21545012. Its totient is φ = 21545010.

The previous prime is 21545009. The next prime is 21545039. The reversal of 21545011 is 11054512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21545011 - 2¹ = 21545009 is a prime.

Together with 21545009, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21545011.

It is not a weakly prime, because it can be changed into another prime (21545311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772505 + 10772506.

It is an arithmetic number, because the mean of its divisors is an integer number (10772506).

Almost surely, 2^21545011 is an apocalyptic number.

21545011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545011 is an equidigital number, since it uses as much as digits as its factorization.

21545011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 21545011 is about 4641.6603710310. The cubic root of 21545011 is about 278.2587992504.

Adding to 21545011 its reverse (11054512), we get a palindrome (32599523).

The spelling of 21545011 in words is "twenty-one million, five hundred forty-five thousand, eleven".