21442770 has 48 divisors (see below), whose sum is σ = 56398680. Its totient is φ = 5651712.

The previous prime is 21442753. The next prime is 21442777. The reversal of 21442770 is 7724412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7177041 + 14265729 = 2679^2 + 3777^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21442777) 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 23 ways as a sum of consecutive naturals, for example, 6672 + ... + 9348.

Almost surely, 2^21442770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21442770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28199340).

21442770 is an abundant number, since it is smaller than the sum of its proper divisors (34955910).

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

21442770 is a wasteful number, since it uses less digits than its factorization.

21442770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2779 (or 2776 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 27.

The square root of 21442770 is about 4630.6338658978. The cubic root of 21442770 is about 277.8179457764.

The spelling of 21442770 in words is "twenty-one million, four hundred forty-two thousand, seven hundred seventy".