21120949 has 2 divisors, whose sum is σ = 21120950. Its totient is φ = 21120948.

The previous prime is 21120947. The next prime is 21120959. The reversal of 21120949 is 94902112.

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., 19298449 + 1822500 = 4393^2 + 1350^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120949 - 2¹ = 21120947 is a prime.

Together with 21120947, it forms a pair of twin primes.

It is equal to p_1337149 and since 21120949 and 1337149 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560474 + 10560475.

It is an arithmetic number, because the mean of its divisors is an integer number (10560475).

Almost surely, 2^21120949 is an apocalyptic number.

It is an amenable number.

21120949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120949 is an equidigital number, since it uses as much as digits as its factorization.

21120949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 21120949 is about 4595.7533658803. The cubic root of 21120949 is about 276.4210692847.

The spelling of 21120949 in words is "twenty-one million, one hundred twenty thousand, nine hundred forty-nine".