21700253 has 2 divisors, whose sum is σ = 21700254. Its totient is φ = 21700252.

The previous prime is 21700243. The next prime is 21700291. The reversal of 21700253 is 35200712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19518724 + 2181529 = 4418^2 + 1477^2 .

It is a cyclic number.

It is not a de Polignac number, because 21700253 - 2¹⁰ = 21699229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21700243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10850126 + 10850127.

It is an arithmetic number, because the mean of its divisors is an integer number (10850127).

Almost surely, 2^21700253 is an apocalyptic number.

It is an amenable number.

21700253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21700253 is an equidigital number, since it uses as much as digits as its factorization.

21700253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21700253 is about 4658.3530351402. The cubic root of 21700253 is about 278.9255292134.

Adding to 21700253 its reverse (35200712), we get a palindrome (56900965).

The spelling of 21700253 in words is "twenty-one million, seven hundred thousand, two hundred fifty-three".