21287250 has 48 divisors (see below), whose sum is σ = 57566808. Its totient is φ = 5676000.

The previous prime is 21287249. The next prime is 21287251. The reversal of 21287250 is 5278212.

It is an interprime number because it is at equal distance from previous prime (21287249) and next prime (21287251).

It can be written as a sum of positive squares in 4 ways, for example, as 8946081 + 12341169 = 2991^2 + 3513^2 .

It is not an unprimeable number, because it can be changed into a prime (21287251) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2481 + ... + 6980.

Almost surely, 2^21287250 is an apocalyptic number.

21287250 is an abundant number, since it is smaller than the sum of its proper divisors (36279558).

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

21287250 is a wasteful number, since it uses less digits than its factorization.

21287250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9484 (or 9471 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21287250 is about 4613.8107893584. The cubic root of 21287250 is about 277.1446632792.

The spelling of 21287250 in words is "twenty-one million, two hundred eighty-seven thousand, two hundred fifty".