21545047 has 2 divisors, whose sum is σ = 21545048. Its totient is φ = 21545046.

The previous prime is 21545039. The next prime is 21545059. The reversal of 21545047 is 74054512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21545047 - 2³ = 21545039 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21545077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772523 + 10772524.

It is an arithmetic number, because the mean of its divisors is an integer number (10772524).

Almost surely, 2^21545047 is an apocalyptic number.

21545047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545047 is an equidigital number, since it uses as much as digits as its factorization.

21545047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21545047 is about 4641.6642489521. The cubic root of 21545047 is about 278.2589542331.

Adding to 21545047 its reverse (74054512), we get a palindrome (95599559).

It can be divided in two parts, 2 and 1545047, that added together give a square (1545049 = 1243²).

The spelling of 21545047 in words is "twenty-one million, five hundred forty-five thousand, forty-seven".