21778011 has 32 divisors (see below), whose sum is σ = 33546240. Its totient is φ = 13953600.

The previous prime is 21778007. The next prime is 21778013. The reversal of 21778011 is 11087712.

It is not a de Polignac number, because 21778011 - 2² = 21778007 is a prime.

It is a super-2 number, since 2×21778011² = 948563526232242, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21778013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 113926 + ... + 114116.

It is an arithmetic number, because the mean of its divisors is an integer number (1048320).

Almost surely, 2^21778011 is an apocalyptic number.

21778011 is a deficient number, since it is larger than the sum of its proper divisors (11768229).

21778011 is a wasteful number, since it uses less digits than its factorization.

21778011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344 (or 338 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 21778011 is about 4666.6916546950. The cubic root of 21778011 is about 279.2582878103.

The spelling of 21778011 in words is "twenty-one million, seven hundred seventy-eight thousand, eleven".