21620983 has 4 divisors (see below), whose sum is σ = 21698208. Its totient is φ = 21543760.

The previous prime is 21620953. The next prime is 21620999. The reversal of 21620983 is 38902612.

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 21620983 - 2⁹ = 21620471 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21620903) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38191 + ... + 38752.

It is an arithmetic number, because the mean of its divisors is an integer number (5424552).

Almost surely, 2^21620983 is an apocalyptic number.

21620983 is a deficient number, since it is larger than the sum of its proper divisors (77225).

21620983 is an equidigital number, since it uses as much as digits as its factorization.

21620983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77224.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21620983 is about 4649.8368788593. The cubic root of 21620983 is about 278.5854808853.

The spelling of 21620983 in words is "twenty-one million, six hundred twenty thousand, nine hundred eighty-three".