21620293 has 4 divisors (see below), whose sum is σ = 21658860. Its totient is φ = 21581728.

The previous prime is 21620279. The next prime is 21620317. The reversal of 21620293 is 39202612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13198689 + 8421604 = 3633^2 + 2902^2 .

It is a cyclic number.

It is not a de Polignac number, because 21620293 - 2⁹ = 21619781 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 (21620273) 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, 18430 + ... + 19567.

It is an arithmetic number, because the mean of its divisors is an integer number (5414715).

Almost surely, 2^21620293 is an apocalyptic number.

It is an amenable number.

21620293 is a deficient number, since it is larger than the sum of its proper divisors (38567).

21620293 is an equidigital number, since it uses as much as digits as its factorization.

21620293 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38566.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21620293 is about 4649.7626821162. The cubic root of 21620293 is about 278.5825173132.

The spelling of 21620293 in words is "twenty-one million, six hundred twenty thousand, two hundred ninety-three".