21029217 has 16 divisors (see below), whose sum is σ = 30716928. Its totient is φ = 12691280.

The previous prime is 21029207. The next prime is 21029237. The reversal of 21029217 is 71292012.

It is a cyclic number.

It is not a de Polignac number, because 21029217 - 2¹¹ = 21027169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21029207) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7468 + ... + 9890.

It is an arithmetic number, because the mean of its divisors is an integer number (1919808).

Almost surely, 2^21029217 is an apocalyptic number.

It is an amenable number.

21029217 is a deficient number, since it is larger than the sum of its proper divisors (9687711).

21029217 is a wasteful number, since it uses less digits than its factorization.

21029217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2700.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21029217 is about 4585.7624229783. The cubic root of 21029217 is about 276.0203067395.

The spelling of 21029217 in words is "twenty-one million, twenty-nine thousand, two hundred seventeen".