21631128 has 32 divisors (see below), whose sum is σ = 54734400. Its totient is φ = 7122848.

The previous prime is 21631121. The next prime is 21631171. The reversal of 21631128 is 82113612.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21631098 and 21631107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631121) 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, 3438 + ... + 7421.

It is an arithmetic number, because the mean of its divisors is an integer number (1710450).

Almost surely, 2^21631128 is an apocalyptic number.

It is an amenable number.

21631128 is an abundant number, since it is smaller than the sum of its proper divisors (33103272).

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

21631128 is a wasteful number, since it uses less digits than its factorization.

21631128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10951 (or 10947 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 21631128 is about 4650.9276494050. The cubic root of 21631128 is about 278.6290467086.

The spelling of 21631128 in words is "twenty-one million, six hundred thirty-one thousand, one hundred twenty-eight".