21931253 has 2 divisors, whose sum is σ = 21931254. Its totient is φ = 21931252.

The previous prime is 21931243. The next prime is 21931271. The reversal of 21931253 is 35213912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 3467044 = 4297^2 + 1862^2 .

It is a cyclic number.

It is not a de Polignac number, because 21931253 - 2⁴ = 21931237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21931223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10965626 + 10965627.

It is an arithmetic number, because the mean of its divisors is an integer number (10965627).

Almost surely, 2^21931253 is an apocalyptic number.

It is an amenable number.

21931253 is a deficient number, since it is larger than the sum of its proper divisors (1).

21931253 is an equidigital number, since it uses as much as digits as its factorization.

21931253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 26.

The square root of 21931253 is about 4683.0815709317. The cubic root of 21931253 is about 279.9117621621.

The spelling of 21931253 in words is "twenty-one million, nine hundred thirty-one thousand, two hundred fifty-three".