21620073 has 16 divisors (see below), whose sum is σ = 30675456. Its totient is φ = 13497600.

The previous prime is 21620063. The next prime is 21620083. The reversal of 21620073 is 37002612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21620063) and next prime (21620083).

It is not a de Polignac number, because 21620073 - 2⁸ = 21619817 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21620003) 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, 10423 + ... + 12323.

It is an arithmetic number, because the mean of its divisors is an integer number (1917216).

Almost surely, 2^21620073 is an apocalyptic number.

It is an amenable number.

21620073 is a deficient number, since it is larger than the sum of its proper divisors (9055383).

21620073 is a wasteful number, since it uses less digits than its factorization.

21620073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21620073 is about 4649.7390249346. The cubic root of 21620073 is about 278.5815723929.

Adding to 21620073 its reverse (37002612), we get a palindrome (58622685).

The spelling of 21620073 in words is "twenty-one million, six hundred twenty thousand, seventy-three".