21135554 has 12 divisors (see below), whose sum is σ = 34847862. Its totient is φ = 9606960.

The previous prime is 21135553. The next prime is 21135559. The reversal of 21135554 is 45553112.

It can be written as a sum of positive squares in only one way, i.e., 20043529 + 1092025 = 4477^2 + 1045^2 .

It is not an unprimeable number, because it can be changed into a prime (21135553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 43427 + ... + 43910.

Almost surely, 2^21135554 is an apocalyptic number.

21135554 is a deficient number, since it is larger than the sum of its proper divisors (13712308).

21135554 is a wasteful number, since it uses less digits than its factorization.

21135554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87361 (or 87350 counting only the distinct ones).

The product of its digits is 3000, while the sum is 26.

The square root of 21135554 is about 4597.3420581897. The cubic root of 21135554 is about 276.4847690664.

Adding to 21135554 its reverse (45553112), we get a palindrome (66688666).

It can be divided in two parts, 2113 and 5554, that added together give a palindrome (7667).

The spelling of 21135554 in words is "twenty-one million, one hundred thirty-five thousand, five hundred fifty-four".