21149550 has 72 divisors (see below), whose sum is σ = 58196424. Its totient is φ = 5503680.

The previous prime is 21149549. The next prime is 21149561. The reversal of 21149550 is 5594112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 18804 + ... + 19896.

Almost surely, 2^21149550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21149550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29098212).

21149550 is an abundant number, since it is smaller than the sum of its proper divisors (37046874).

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

21149550 is a wasteful number, since it uses less digits than its factorization.

21149550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1154 (or 1146 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 21149550 is about 4598.8639901610. The cubic root of 21149550 is about 276.5457851624.

It can be divided in two parts, 2114 and 9550, that added together give a square (11664 = 108²).

The spelling of 21149550 in words is "twenty-one million, one hundred forty-nine thousand, five hundred fifty".