21777745 has 8 divisors (see below), whose sum is σ = 28509120. Its totient is φ = 15838320.

The previous prime is 21777727. The next prime is 21777751. The reversal of 21777745 is 54777712.

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

It is not a de Polignac number, because 21777745 - 2⁵ = 21777713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21777698 and 21777707.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197925 + ... + 198034.

It is an arithmetic number, because the mean of its divisors is an integer number (3563640).

Almost surely, 2^21777745 is an apocalyptic number.

It is an amenable number.

21777745 is a deficient number, since it is larger than the sum of its proper divisors (6731375).

21777745 is a wasteful number, since it uses less digits than its factorization.

21777745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395975.

The product of its digits is 96040, while the sum is 40.

The square root of 21777745 is about 4666.6631547606. The cubic root of 21777745 is about 279.2571508377.

It can be divided in two parts, 21777 and 745, that added together give a palindrome (22522).

The spelling of 21777745 in words is "twenty-one million, seven hundred seventy-seven thousand, seven hundred forty-five".