21231253 has 2 divisors, whose sum is σ = 21231254. Its totient is φ = 21231252.

The previous prime is 21231241. The next prime is 21231269. The reversal of 21231253 is 35213212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15194404 + 6036849 = 3898^2 + 2457^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231253 - 2¹³ = 21223061 is a prime.

It is a super-2 number, since 2×21231253² = 901532207900018, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21231253.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21271253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615626 + 10615627.

It is an arithmetic number, because the mean of its divisors is an integer number (10615627).

Almost surely, 2^21231253 is an apocalyptic number.

It is an amenable number.

21231253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231253 is an equidigital number, since it uses as much as digits as its factorization.

21231253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 360, while the sum is 19.

The square root of 21231253 is about 4607.7383823303. The cubic root of 21231253 is about 276.9014363451.

Adding to 21231253 its reverse (35213212), we get a palindrome (56444465).

The spelling of 21231253 in words is "twenty-one million, two hundred thirty-one thousand, two hundred fifty-three".