21700128 has 48 divisors (see below), whose sum is σ = 59965920. Its totient is φ = 6852096.

The previous prime is 21700127. The next prime is 21700169. The reversal of 21700128 is 82100712.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21700123) 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, 4125 + ... + 7772.

It is an arithmetic number, because the mean of its divisors is an integer number (1249290).

Almost surely, 2^21700128 is an apocalyptic number.

It is an amenable number.

21700128 is an abundant number, since it is smaller than the sum of its proper divisors (38265792).

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

21700128 is a wasteful number, since it uses less digits than its factorization.

21700128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11929 (or 11921 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 21700128 is about 4658.3396183619. The cubic root of 21700128 is about 278.9249936473.

The spelling of 21700128 in words is "twenty-one million, seven hundred thousand, one hundred twenty-eight".