21946428 has 72 divisors (see below), whose sum is σ = 64323168. Its totient is φ = 6179328.

The previous prime is 21946427. The next prime is 21946447. The reversal of 21946428 is 82464912.

21946428 is a `hidden beast` number, since 2 + 1 + 9 + 4 + 642 + 8 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21946392 and 21946401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21946423) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17800 + ... + 18992.

Almost surely, 2^21946428 is an apocalyptic number.

21946428 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 21946428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32161584).

21946428 is an abundant number, since it is smaller than the sum of its proper divisors (42376740).

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

21946428 is a wasteful number, since it uses less digits than its factorization.

21946428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1283 (or 1278 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21946428 is about 4684.7014846199. The cubic root of 21946428 is about 279.9763075191.

The spelling of 21946428 in words is "twenty-one million, nine hundred forty-six thousand, four hundred twenty-eight".