21699828 has 18 divisors (see below), whose sum is σ = 54852434. Its totient is φ = 7233264.

The previous prime is 21699827. The next prime is 21699857. The reversal of 21699828 is 82899612.

It can be written as a sum of positive squares in only one way, i.e., 17489124 + 4210704 = 4182^2 + 2052^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21699823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 301351 + ... + 301422.

Almost surely, 2^21699828 is an apocalyptic number.

It is an amenable number.

21699828 is an abundant number, since it is smaller than the sum of its proper divisors (33152606).

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

21699828 is a wasteful number, since it uses less digits than its factorization.

21699828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 602783 (or 602778 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 21699828 is about 4658.3074179363. The cubic root of 21699828 is about 278.9237082803.

The spelling of 21699828 in words is "twenty-one million, six hundred ninety-nine thousand, eight hundred twenty-eight".