21871049 has 2 divisors, whose sum is σ = 21871050. Its totient is φ = 21871048.

The previous prime is 21871043. The next prime is 21871067. The reversal of 21871049 is 94017812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21557449 + 313600 = 4643^2 + 560^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21871049 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21871043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10935524 + 10935525.

It is an arithmetic number, because the mean of its divisors is an integer number (10935525).

Almost surely, 2^21871049 is an apocalyptic number.

It is an amenable number.

21871049 is a deficient number, since it is larger than the sum of its proper divisors (1).

21871049 is an equidigital number, since it uses as much as digits as its factorization.

21871049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 21871049 is about 4676.6493347267. The cubic root of 21871049 is about 279.6553966398.

The spelling of 21871049 in words is "twenty-one million, eight hundred seventy-one thousand, forty-nine".