21503653 has 2 divisors, whose sum is σ = 21503654. Its totient is φ = 21503652.

The previous prime is 21503621. The next prime is 21503693. The reversal of 21503653 is 35630512.

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., 13786369 + 7717284 = 3713^2 + 2778^2 .

It is a cyclic number.

It is not a de Polignac number, because 21503653 - 2⁵ = 21503621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21503693) 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, 10751826 + 10751827.

It is an arithmetic number, because the mean of its divisors is an integer number (10751827).

Almost surely, 2^21503653 is an apocalyptic number.

It is an amenable number.

21503653 is a deficient number, since it is larger than the sum of its proper divisors (1).

21503653 is an equidigital number, since it uses as much as digits as its factorization.

21503653 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2700, while the sum is 25.

The square root of 21503653 is about 4637.2031441376. The cubic root of 21503653 is about 278.0806358224.

The spelling of 21503653 in words is "twenty-one million, five hundred three thousand, six hundred fifty-three".