21011249 has 6 divisors (see below), whose sum is σ = 24441714. Its totient is φ = 18009600.

The previous prime is 21011239. The next prime is 21011251. The reversal of 21011249 is 94211012.

It can be written as a sum of positive squares in only one way, i.e., 17698849 + 3312400 = 4207^2 + 1820^2 .

It is not a de Polignac number, because 21011249 - 2⁴ = 21011233 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21011249.

It is not an unprimeable number, because it can be changed into a prime (21011239) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 214352 + ... + 214449.

It is an arithmetic number, because the mean of its divisors is an integer number (4073619).

Almost surely, 2^21011249 is an apocalyptic number.

It is an amenable number.

21011249 is a deficient number, since it is larger than the sum of its proper divisors (3430465).

21011249 is an equidigital number, since it uses as much as digits as its factorization.

21011249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428815 (or 428808 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 21011249 is about 4583.8028971586. The cubic root of 21011249 is about 275.9416709686.

The spelling of 21011249 in words is "twenty-one million, eleven thousand, two hundred forty-nine".