21620603 has 2 divisors, whose sum is σ = 21620604. Its totient is φ = 21620602.

The previous prime is 21620597. The next prime is 21620659. The reversal of 21620603 is 30602612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21620603 - 2¹⁰ = 21619579 is a prime.

It is not a weakly prime, because it can be changed into another prime (21620693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810301 + 10810302.

It is an arithmetic number, because the mean of its divisors is an integer number (10810302).

Almost surely, 2^21620603 is an apocalyptic number.

21620603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620603 is an equidigital number, since it uses as much as digits as its factorization.

21620603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21620603 is about 4649.7960170313. The cubic root of 21620603 is about 278.5838487809.

Subtracting 21620603 from its reverse (30602612), we obtain a square (8982009 = 2997²).

The spelling of 21620603 in words is "twenty-one million, six hundred twenty thousand, six hundred three".