21127881 has 8 divisors (see below), whose sum is σ = 28191744. Its totient is φ = 14074640.

The previous prime is 21127877. The next prime is 21127901. The reversal of 21127881 is 18872112.

It is a happy number.

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 21127881 - 2² = 21127877 is a prime.

It is a super-2 number, since 2×21127881² = 892774711100322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21127081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6520 + ... + 9206.

It is an arithmetic number, because the mean of its divisors is an integer number (3523968).

Almost surely, 2^21127881 is an apocalyptic number.

It is an amenable number.

21127881 is a deficient number, since it is larger than the sum of its proper divisors (7063863).

21127881 is a wasteful number, since it uses less digits than its factorization.

21127881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5311.

The product of its digits is 1792, while the sum is 30.

The square root of 21127881 is about 4596.5074785102. The cubic root of 21127881 is about 276.4513068979.

Adding to 21127881 its reverse (18872112), we get a palindrome (39999993).

The spelling of 21127881 in words is "twenty-one million, one hundred twenty-seven thousand, eight hundred eighty-one".