21471881 has 4 divisors (see below), whose sum is σ = 22602000. Its totient is φ = 20341764.

The previous prime is 21471839. The next prime is 21471883. The reversal of 21471881 is 18817412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21471881 is a prime.

It is a super-2 number, since 2×21471881² = 922083347356322, 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 (21471883) 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 3 ways as a sum of consecutive naturals, for example, 565031 + ... + 565068.

It is an arithmetic number, because the mean of its divisors is an integer number (5650500).

Almost surely, 2^21471881 is an apocalyptic number.

It is an amenable number.

21471881 is a deficient number, since it is larger than the sum of its proper divisors (1130119).

21471881 is a wasteful number, since it uses less digits than its factorization.

21471881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1130118.

The product of its digits is 3584, while the sum is 32.

The square root of 21471881 is about 4633.7761059421. The cubic root of 21471881 is about 277.9436120818.

The spelling of 21471881 in words is "twenty-one million, four hundred seventy-one thousand, eight hundred eighty-one".