21055552 has 56 divisors (see below), whose sum is σ = 48906176. Its totient is φ = 8805888.

The previous prime is 21055543. The next prime is 21055561. The reversal of 21055552 is 25555012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21055543) and next prime (21055561).

It is a tau number, because it is divible by the number of its divisors (56).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18718 + ... + 19810.

Almost surely, 2^21055552 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21055552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24453088).

21055552 is an abundant number, since it is smaller than the sum of its proper divisors (27850624).

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

21055552 is a wasteful number, since it uses less digits than its factorization.

21055552 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155 (or 1145 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 25.

The square root of 21055552 is about 4588.6329118813. The cubic root of 21055552 is about 276.1354792405.

It can be divided in two parts, 210555 and 52, that multiplied together give a triangular number (10948860 = T₄₆₇₉).

The spelling of 21055552 in words is "twenty-one million, fifty-five thousand, five hundred fifty-two".