21554720 has 96 divisors (see below), whose sum is σ = 57226176. Its totient is φ = 7603200.

The previous prime is 21554711. The next prime is 21554723. The reversal of 21554720 is 2745512.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21554720.

It is not an unprimeable number, because it can be changed into a prime (21554723) 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, 64955 + ... + 65285.

It is an arithmetic number, because the mean of its divisors is an integer number (596106).

Almost surely, 2^21554720 is an apocalyptic number.

21554720 is a gapful number since it is divisible by the number (20) 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 21554720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28613088).

21554720 is an abundant number, since it is smaller than the sum of its proper divisors (35671456).

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

21554720 is a wasteful number, since it uses less digits than its factorization.

21554720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 386 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21554720 is about 4642.7061074335. The cubic root of 21554720 is about 278.3005909668.

The spelling of 21554720 in words is "twenty-one million, five hundred fifty-four thousand, seven hundred twenty".