21001049 has 2 divisors, whose sum is σ = 21001050. Its totient is φ = 21001048.

The previous prime is 21001037. The next prime is 21001081. The reversal of 21001049 is 94010012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20976400 + 24649 = 4580^2 + 157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001049 - 2⁴ = 21001033 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21001349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500524 + 10500525.

It is an arithmetic number, because the mean of its divisors is an integer number (10500525).

Almost surely, 2^21001049 is an apocalyptic number.

It is an amenable number.

21001049 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001049 is an equidigital number, since it uses as much as digits as its factorization.

21001049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21001049 is about 4582.6901488100. The cubic root of 21001049 is about 275.8970113893.

The spelling of 21001049 in words is "twenty-one million, one thousand, forty-nine".