21742028 has 48 divisors (see below), whose sum is σ = 48136704. Its totient is φ = 8346240.

The previous prime is 21742027. The next prime is 21742033. The reversal of 21742028 is 82024712.

It is a super-3 number, since 3×21742028³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21741988 and 21742006.

It is not an unprimeable number, because it can be changed into a prime (21742027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22001 + ... + 22967.

It is an arithmetic number, because the mean of its divisors is an integer number (1002848).

Almost surely, 2^21742028 is an apocalyptic number.

21742028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21742028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24068352).

21742028 is an abundant number, since it is smaller than the sum of its proper divisors (26394676).

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

21742028 is a wasteful number, since it uses less digits than its factorization.

21742028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1062 (or 1060 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 21742028 is about 4662.8347601003. The cubic root of 21742028 is about 279.1044003205.

The spelling of 21742028 in words is "twenty-one million, seven hundred forty-two thousand, twenty-eight".