21591270 has 48 divisors (see below), whose sum is σ = 56609280. Its totient is φ = 5709312.

The previous prime is 21591259. The next prime is 21591281. The reversal of 21591270 is 7219512.

21591270 is a `hidden beast` number, since 2 + 1 + 591 + 2 + 70 = 666.

It is an interprime number because it is at equal distance from previous prime (21591259) and next prime (21591281).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 10486 + ... + 12374.

It is an arithmetic number, because the mean of its divisors is an integer number (1179360).

Almost surely, 2^21591270 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21591270, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28304640).

21591270 is an abundant number, since it is smaller than the sum of its proper divisors (35018010).

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

21591270 is a wasteful number, since it uses less digits than its factorization.

21591270 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2029 (or 2026 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21591270 is about 4646.6407220701. The cubic root of 21591270 is about 278.4578054512.

The spelling of 21591270 in words is "twenty-one million, five hundred ninety-one thousand, two hundred seventy".