21071250 has 60 divisors (see below), whose sum is σ = 57080166. Its totient is φ = 5616000.

The previous prime is 21071249. The next prime is 21071251. The reversal of 21071250 is 5217012.

It is an interprime number because it is at equal distance from previous prime (21071249) and next prime (21071251).

It can be written as a sum of positive squares in 5 ways, for example, as 848241 + 20223009 = 921^2 + 4497^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071251) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 10314 + ... + 12186.

Almost surely, 2^21071250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21071250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28540083).

21071250 is an abundant number, since it is smaller than the sum of its proper divisors (36008916).

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

21071250 is a wasteful number, since it uses less digits than its factorization.

21071250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1901 (or 1883 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21071250 is about 4590.3431244298. The cubic root of 21071250 is about 276.2040866073.

Adding to 21071250 its reverse (5217012), we get a palindrome (26288262).

It can be divided in two parts, 21071 and 250, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21071250 in words is "twenty-one million, seventy-one thousand, two hundred fifty".