21739770 has 96 divisors (see below), whose sum is σ = 64510992. Its totient is φ = 5031936.

The previous prime is 21739759. The next prime is 21739771. The reversal of 21739770 is 7793712.

It can be written as a sum of positive squares in 8 ways, for example, as 15374241 + 6365529 = 3921^2 + 2523^2 .

It is not an unprimeable number, because it can be changed into a prime (21739771) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19344 + ... + 20436.

Almost surely, 2^21739770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21739770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32255496).

21739770 is an abundant number, since it is smaller than the sum of its proper divisors (42771222).

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

21739770 is a wasteful number, since it uses less digits than its factorization.

21739770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1136 (or 1133 counting only the distinct ones).

The product of its (nonzero) digits is 18522, while the sum is 36.

The square root of 21739770 is about 4662.5926264258. The cubic root of 21739770 is about 279.0947379352.

The spelling of 21739770 in words is "twenty-one million, seven hundred thirty-nine thousand, seven hundred seventy".