21778563 has 8 divisors (see below), whose sum is σ = 29059776. Its totient is φ = 14508200.

The previous prime is 21778543. The next prime is 21778573. The reversal of 21778563 is 36587712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21778563 - 2⁶ = 21778499 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21778543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5728 + ... + 8738.

It is an arithmetic number, because the mean of its divisors is an integer number (3632472).

Almost surely, 2^21778563 is an apocalyptic number.

21778563 is a deficient number, since it is larger than the sum of its proper divisors (7281213).

21778563 is a wasteful number, since it uses less digits than its factorization.

21778563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5425.

The product of its digits is 70560, while the sum is 39.

The square root of 21778563 is about 4666.7507968607. The cubic root of 21778563 is about 279.2606472127.

The spelling of 21778563 in words is "twenty-one million, seven hundred seventy-eight thousand, five hundred sixty-three".