21365501 has 2 divisors, whose sum is σ = 21365502. Its totient is φ = 21365500.

The previous prime is 21365497. The next prime is 21365521. The reversal of 21365501 is 10556312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16080100 + 5285401 = 4010^2 + 2299^2 .

It is a cyclic number.

It is not a de Polignac number, because 21365501 - 2² = 21365497 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21365521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10682750 + 10682751.

It is an arithmetic number, because the mean of its divisors is an integer number (10682751).

Almost surely, 2^21365501 is an apocalyptic number.

It is an amenable number.

21365501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21365501 is an equidigital number, since it uses as much as digits as its factorization.

21365501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21365501 is about 4622.2830938834. The cubic root of 21365501 is about 277.4838385740.

The spelling of 21365501 in words is "twenty-one million, three hundred sixty-five thousand, five hundred one".