21025949 has 6 divisors (see below), whose sum is σ = 24458814. Its totient is φ = 18022200.

The previous prime is 21025937. The next prime is 21025981. The reversal of 21025949 is 94952012.

It can be written as a sum of positive squares in only one way, i.e., 17347225 + 3678724 = 4165^2 + 1918^2 .

It is not a de Polignac number, because 21025949 - 2¹⁶ = 20960413 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025909) 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 in 5 ways as a sum of consecutive naturals, for example, 214502 + ... + 214599.

It is an arithmetic number, because the mean of its divisors is an integer number (4076469).

Almost surely, 2^21025949 is an apocalyptic number.

It is an amenable number.

21025949 is a deficient number, since it is larger than the sum of its proper divisors (3432865).

21025949 is an equidigital number, since it uses as much as digits as its factorization.

21025949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429115 (or 429108 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 21025949 is about 4585.4060888868. The cubic root of 21025949 is about 276.0060078857.

The spelling of 21025949 in words is "twenty-one million, twenty-five thousand, nine hundred forty-nine".