21388950 has 144 divisors (see below), whose sum is σ = 65286000. Its totient is φ = 4972800.

The previous prime is 21388949. The next prime is 21388957. The reversal of 21388950 is 5988312.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21388957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 143476 + ... + 143624.

It is an arithmetic number, because the mean of its divisors is an integer number (453375).

Almost surely, 2^21388950 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21388950, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32643000).

21388950 is an abundant number, since it is smaller than the sum of its proper divisors (43897050).

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

21388950 is a wasteful number, since it uses less digits than its factorization.

21388950 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 207 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21388950 is about 4624.8189153739. The cubic root of 21388950 is about 277.5853158663.

The spelling of 21388950 in words is "twenty-one million, three hundred eighty-eight thousand, nine hundred fifty".