21571903 has 2 divisors, whose sum is σ = 21571904. Its totient is φ = 21571902.

The previous prime is 21571867. The next prime is 21571933. The reversal of 21571903 is 30917512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21571903 is a prime.

It is a plaindrome in base 8.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21571933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10785951 + 10785952.

It is an arithmetic number, because the mean of its divisors is an integer number (10785952).

Almost surely, 2^21571903 is an apocalyptic number.

21571903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21571903 is an equidigital number, since it uses as much as digits as its factorization.

21571903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21571903 is about 4644.5562758998. The cubic root of 21571903 is about 278.3745232486.

The spelling of 21571903 in words is "twenty-one million, five hundred seventy-one thousand, nine hundred three".