21751028 has 12 divisors (see below), whose sum is σ = 40992420. Its totient is φ = 10038912.

The previous prime is 21751027. The next prime is 21751039. The reversal of 21751028 is 82015712.

It can be written as a sum of positive squares in 2 ways, for example, as 5654884 + 16096144 = 2378^2 + 4012^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a junction number, because it is equal to n+sod(n) for n = 21750988 and 21751006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 209093 + ... + 209196.

It is an arithmetic number, because the mean of its divisors is an integer number (3416035).

Almost surely, 2^21751028 is an apocalyptic number.

It is an amenable number.

21751028 is a deficient number, since it is larger than the sum of its proper divisors (19241392).

21751028 is a wasteful number, since it uses less digits than its factorization.

21751028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418306 (or 418304 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21751028 is about 4663.7997384107. The cubic root of 21751028 is about 279.1429062820.

The spelling of 21751028 in words is "twenty-one million, seven hundred fifty-one thousand, twenty-eight".