21779345 has 16 divisors (see below), whose sum is σ = 29971200. Its totient is φ = 14883264.

The previous prime is 21779341. The next prime is 21779383. The reversal of 21779345 is 54397712.

It is a cyclic number.

It is not a de Polignac number, because 21779345 - 2² = 21779341 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21779299 and 21779308.

It is not an unprimeable number, because it can be changed into a prime (21779341) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 11324 + ... + 13106.

It is an arithmetic number, because the mean of its divisors is an integer number (1873200).

Almost surely, 2^21779345 is an apocalyptic number.

It is an amenable number.

21779345 is a deficient number, since it is larger than the sum of its proper divisors (8191855).

21779345 is a wasteful number, since it uses less digits than its factorization.

21779345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144.

The product of its digits is 52920, while the sum is 38.

The square root of 21779345 is about 4666.8345803124. The cubic root of 21779345 is about 279.2639896311.

The spelling of 21779345 in words is "twenty-one million, seven hundred seventy-nine thousand, three hundred forty-five".