21870029 has 2 divisors, whose sum is σ = 21870030. Its totient is φ = 21870028.

The previous prime is 21870011. The next prime is 21870047. The reversal of 21870029 is 92007812.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (21870011) and next prime (21870047).

It can be written as a sum of positive squares in only one way, i.e., 17556100 + 4313929 = 4190^2 + 2077^2 .

It is a cyclic number.

It is not a de Polignac number, because 21870029 - 2¹⁶ = 21804493 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21869983 and 21870010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21870229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10935014 + 10935015.

It is an arithmetic number, because the mean of its divisors is an integer number (10935015).

Almost surely, 2^21870029 is an apocalyptic number.

It is an amenable number.

21870029 is a deficient number, since it is larger than the sum of its proper divisors (1).

21870029 is an equidigital number, since it uses as much as digits as its factorization.

21870029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21870029 is about 4676.5402810197. The cubic root of 21870029 is about 279.6510491431.

The spelling of 21870029 in words is "twenty-one million, eight hundred seventy thousand, twenty-nine".