21670828 has 6 divisors (see below), whose sum is σ = 37923956. Its totient is φ = 10835412.

The previous prime is 21670819. The next prime is 21670861. The reversal of 21670828 is 82807612.

It is a junction number, because it is equal to n+sod(n) for n = 21670793 and 21670802.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2708850 + ... + 2708857.

Almost surely, 2^21670828 is an apocalyptic number.

It is an amenable number.

21670828 is a deficient number, since it is larger than the sum of its proper divisors (16253128).

21670828 is a wasteful number, since it uses less digits than its factorization.

21670828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5417711 (or 5417709 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 21670828 is about 4655.1936586999. The cubic root of 21670828 is about 278.7994001745.

The spelling of 21670828 in words is "twenty-one million, six hundred seventy thousand, eight hundred twenty-eight".