21601590 has 16 divisors (see below), whose sum is σ = 51843888. Its totient is φ = 5760416.

The previous prime is 21601579. The next prime is 21601597. The reversal of 21601590 is 9510612.

It is a self number, because there is not a number n which added to its sum of digits gives 21601590.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21601597) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 359997 + ... + 360056.

It is an arithmetic number, because the mean of its divisors is an integer number (3240243).

Almost surely, 2^21601590 is an apocalyptic number.

21601590 is an abundant number, since it is smaller than the sum of its proper divisors (30242298).

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

21601590 is a wasteful number, since it uses less digits than its factorization.

21601590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 720063.

The product of its (nonzero) digits is 540, while the sum is 24.

The square root of 21601590 is about 4647.7510690656. The cubic root of 21601590 is about 278.5021632993.

The spelling of 21601590 in words is "twenty-one million, six hundred one thousand, five hundred ninety".