21155552 has 24 divisors (see below), whose sum is σ = 45437112. Its totient is φ = 9616000.

The previous prime is 21155551. The next prime is 21155591. The reversal of 21155552 is 25555112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155551) 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 in 3 ways as a sum of consecutive naturals, for example, 29699 + ... + 30402.

It is an arithmetic number, because the mean of its divisors is an integer number (1893213).

Almost surely, 2^21155552 is an apocalyptic number.

21155552 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21155552 is an abundant number, since it is smaller than the sum of its proper divisors (24281560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21155552 is a wasteful number, since it uses less digits than its factorization.

21155552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60122 (or 60114 counting only the distinct ones).

The product of its digits is 2500, while the sum is 26.

The square root of 21155552 is about 4599.5164963287. The cubic root of 21155552 is about 276.5719428633.

It can be divided in two parts, 2115 and 5552, that added together give a palindrome (7667).

The spelling of 21155552 in words is "twenty-one million, one hundred fifty-five thousand, five hundred fifty-two".