6821290021 has 16 divisors (see below), whose sum is σ = 8760455424. Its totient is φ = 5162408064.

The previous prime is 6821290009. The next prime is 6821290027. The reversal of 6821290021 is 1200921286.

It is a cyclic number.

It is not a de Polignac number, because 6821290021 - 2⁵ = 6821289989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6821290027) 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 15 ways as a sum of consecutive naturals, for example, 1627456 + ... + 1631641.

It is an arithmetic number, because the mean of its divisors is an integer number (547528464).

Almost surely, 2^6821290021 is an apocalyptic number.

It is an amenable number.

6821290021 is a deficient number, since it is larger than the sum of its proper divisors (1939165403).

6821290021 is a wasteful number, since it uses less digits than its factorization.

6821290021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3259140.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 6821290021 is about 82591.1013426991. The cubic root of 6821290021 is about 1896.5116067212.

The spelling of 6821290021 in words is "six billion, eight hundred twenty-one million, two hundred ninety thousand, twenty-one".