21745386 has 96 divisors (see below), whose sum is σ = 54949440. Its totient is φ = 6158592.

The previous prime is 21745379. The next prime is 21745387. The reversal of 21745386 is 68354712.

Its product of digits (40320) is a multiple of the sum of its prime factors (180).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21745386.

It is not an unprimeable number, because it can be changed into a prime (21745387) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 297846 + ... + 297918.

It is an arithmetic number, because the mean of its divisors is an integer number (572390).

Almost surely, 2^21745386 is an apocalyptic number.

21745386 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21745386, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27474720).

21745386 is an abundant number, since it is smaller than the sum of its proper divisors (33204054).

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

21745386 is a wasteful number, since it uses less digits than its factorization.

21745386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180 (or 177 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21745386 is about 4663.1948275833. The cubic root of 21745386 is about 279.1187685651.

The spelling of 21745386 in words is "twenty-one million, seven hundred forty-five thousand, three hundred eighty-six".