21870047 has 2 divisors, whose sum is σ = 21870048. Its totient is φ = 21870046.

The previous prime is 21870029. The next prime is 21870053. The reversal of 21870047 is 74007812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21870047 - 2⁶ = 21869983 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21870547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10935023 + 10935024.

It is an arithmetic number, because the mean of its divisors is an integer number (10935024).

Almost surely, 2^21870047 is an apocalyptic number.

21870047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21870047 is an equidigital number, since it uses as much as digits as its factorization.

21870047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 21870047 is about 4676.5422055189. The cubic root of 21870047 is about 279.6511258648.

Adding to 21870047 its reverse (74007812), we get a palindrome (95877859).

The spelling of 21870047 in words is "twenty-one million, eight hundred seventy thousand, forty-seven".