21392028 has 108 divisors (see below), whose sum is σ = 64194312. Its totient is φ = 5987520.

The previous prime is 21392023. The next prime is 21392051. The reversal of 21392028 is 82029312.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21391992 and 21392010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21392023) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 118098 + ... + 118278.

Almost surely, 2^21392028 is an apocalyptic number.

21392028 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 21392028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32097156).

21392028 is an abundant number, since it is smaller than the sum of its proper divisors (42802284).

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

21392028 is a wasteful number, since it uses less digits than its factorization.

21392028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 260 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21392028 is about 4625.1516731887. The cubic root of 21392028 is about 277.5986306327.

The spelling of 21392028 in words is "twenty-one million, three hundred ninety-two thousand, twenty-eight".