21948444 has 72 divisors (see below), whose sum is σ = 63842688. Its totient is φ = 6228000.

The previous prime is 21948427. The next prime is 21948457. The reversal of 21948444 is 44484912.

It is a super-2 number, since 2×21948444² = 963468388042272, which contains 22 as substring.

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 = 21948399 and 21948408.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 63079 + ... + 63425.

It is an arithmetic number, because the mean of its divisors is an integer number (886704).

Almost surely, 2^21948444 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21948444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31921344).

21948444 is an abundant number, since it is smaller than the sum of its proper divisors (41894244).

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

21948444 is a wasteful number, since it uses less digits than its factorization.

21948444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 615 (or 610 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 21948444 is about 4684.9166481379. The cubic root of 21948444 is about 279.9848801359.

The spelling of 21948444 in words is "twenty-one million, nine hundred forty-eight thousand, four hundred forty-four".