21035553 has 24 divisors (see below), whose sum is σ = 35595360. Its totient is φ = 10926720.

The previous prime is 21035551. The next prime is 21035561. The reversal of 21035553 is 35553012.

It is not a de Polignac number, because 21035553 - 2¹ = 21035551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21035551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4888 + ... + 8121.

It is an arithmetic number, because the mean of its divisors is an integer number (1483140).

Almost surely, 2^21035553 is an apocalyptic number.

It is an amenable number.

21035553 is a deficient number, since it is larger than the sum of its proper divisors (14559807).

21035553 is a wasteful number, since it uses less digits than its factorization.

21035553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13037 (or 13030 counting only the distinct ones).

The product of its (nonzero) digits is 2250, while the sum is 24.

The square root of 21035553 is about 4586.4532048196. The cubic root of 21035553 is about 276.0480251443.

Adding to 21035553 its reverse (35553012), we get a palindrome (56588565).

The spelling of 21035553 in words is "twenty-one million, thirty-five thousand, five hundred fifty-three".