21002953 has 2 divisors, whose sum is σ = 21002954. Its totient is φ = 21002952.

The previous prime is 21002941. The next prime is 21002957. The reversal of 21002953 is 35920012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20358144 + 644809 = 4512^2 + 803^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002953 - 2⁵ = 21002921 is a prime.

It is a super-3 number, since 3×21002953³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (21002957) 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, 10501476 + 10501477.

It is an arithmetic number, because the mean of its divisors is an integer number (10501477).

Almost surely, 2^21002953 is an apocalyptic number.

It is an amenable number.

21002953 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002953 is an equidigital number, since it uses as much as digits as its factorization.

21002953 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 21002953 is about 4582.8978823448. The cubic root of 21002953 is about 275.9053489417.

Adding to 21002953 its reverse (35920012), we get a palindrome (56922965).

The spelling of 21002953 in words is "twenty-one million, two thousand, nine hundred fifty-three".