21029867 has 4 divisors (see below), whose sum is σ = 22266936. Its totient is φ = 19792800.

The previous prime is 21029857. The next prime is 21029951. The reversal of 21029867 is 76892012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21029867 - 2¹⁴ = 21013483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21029837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 618509 + ... + 618542.

It is an arithmetic number, because the mean of its divisors is an integer number (5566734).

Almost surely, 2^21029867 is an apocalyptic number.

21029867 is a deficient number, since it is larger than the sum of its proper divisors (1237069).

21029867 is a wasteful number, since it uses less digits than its factorization.

21029867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237068.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 21029867 is about 4585.8332939609. The cubic root of 21029867 is about 276.0231505821.

The spelling of 21029867 in words is "twenty-one million, twenty-nine thousand, eight hundred sixty-seven".