21620867 has 4 divisors (see below), whose sum is σ = 21630576. Its totient is φ = 21611160.

The previous prime is 21620843. The next prime is 21620869. The reversal of 21620867 is 76802612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21620867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21620869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 338 + ... + 6584.

It is an arithmetic number, because the mean of its divisors is an integer number (5407644).

Almost surely, 2^21620867 is an apocalyptic number.

21620867 is a deficient number, since it is larger than the sum of its proper divisors (9709).

21620867 is an equidigital number, since it uses as much as digits as its factorization.

21620867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9708.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 21620867 is about 4649.8244052867. The cubic root of 21620867 is about 278.5849826660.

The spelling of 21620867 in words is "twenty-one million, six hundred twenty thousand, eight hundred sixty-seven".