21870229 has 2 divisors, whose sum is σ = 21870230. Its totient is φ = 21870228.

The previous prime is 21870227. The next prime is 21870239. The reversal of 21870229 is 92207812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13616100 + 8254129 = 3690^2 + 2873^2 .

It is a cyclic number.

It is not a de Polignac number, because 21870229 - 2¹ = 21870227 is a prime.

Together with 21870227, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21870229.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21870223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10935114 + 10935115.

It is an arithmetic number, because the mean of its divisors is an integer number (10935115).

Almost surely, 2^21870229 is an apocalyptic number.

It is an amenable number.

21870229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21870229 is an equidigital number, since it uses as much as digits as its factorization.

21870229 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 31.

The square root of 21870229 is about 4676.5616643000. The cubic root of 21870229 is about 279.6519016041.

The spelling of 21870229 in words is "twenty-one million, eight hundred seventy thousand, two hundred twenty-nine".