21871799 has 2 divisors, whose sum is σ = 21871800. Its totient is φ = 21871798.

The previous prime is 21871783. The next prime is 21871807. The reversal of 21871799 is 99717812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21871799 - 2⁴ = 21871783 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 (21871739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10935899 + 10935900.

It is an arithmetic number, because the mean of its divisors is an integer number (10935900).

Almost surely, 2^21871799 is an apocalyptic number.

21871799 is a deficient number, since it is larger than the sum of its proper divisors (1).

21871799 is an equidigital number, since it uses as much as digits as its factorization.

21871799 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63504, while the sum is 44.

The square root of 21871799 is about 4676.7295196537. The cubic root of 21871799 is about 279.6585932423.

The spelling of 21871799 in words is "twenty-one million, eight hundred seventy-one thousand, seven hundred ninety-nine".