21021349 has 2 divisors, whose sum is σ = 21021350. Its totient is φ = 21021348.

The previous prime is 21021331. The next prime is 21021359. The reversal of 21021349 is 94312012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14861025 + 6160324 = 3855^2 + 2482^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021349 - 2⁹ = 21020837 is a prime.

It is a super-2 number, since 2×21021349² = 883794227559602, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510674 + 10510675.

It is an arithmetic number, because the mean of its divisors is an integer number (10510675).

Almost surely, 2^21021349 is an apocalyptic number.

It is an amenable number.

21021349 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021349 is an equidigital number, since it uses as much as digits as its factorization.

21021349 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21021349 is about 4584.9044701062. The cubic root of 21021349 is about 275.9858784695.

The spelling of 21021349 in words is "twenty-one million, twenty-one thousand, three hundred forty-nine".