21603881 has 8 divisors (see below), whose sum is σ = 23331840. Its totient is φ = 19885392.

The previous prime is 21603871. The next prime is 21603899. The reversal of 21603881 is 18830612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21603881 - 2¹⁸ = 21341737 is a prime.

It is a super-2 number, since 2×21603881² = 933455348524322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21603851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2810 + ... + 7148.

It is an arithmetic number, because the mean of its divisors is an integer number (2916480).

Almost surely, 2^21603881 is an apocalyptic number.

It is an amenable number.

21603881 is a deficient number, since it is larger than the sum of its proper divisors (1727959).

21603881 is a wasteful number, since it uses less digits than its factorization.

21603881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4735.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21603881 is about 4647.9975258169. The cubic root of 21603881 is about 278.5120086533.

The spelling of 21603881 in words is "twenty-one million, six hundred three thousand, eight hundred eighty-one".