21778401 has 12 divisors (see below), whose sum is σ = 30357488. Its totient is φ = 13886664.

The previous prime is 21778387. The next prime is 21778409. The reversal of 21778401 is 10487712.

It is not a de Polignac number, because 21778401 - 2⁵ = 21778369 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21778409) 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 11 ways as a sum of consecutive naturals, for example, 5275 + ... + 8448.

Almost surely, 2^21778401 is an apocalyptic number.

It is an amenable number.

21778401 is a deficient number, since it is larger than the sum of its proper divisors (8579087).

21778401 is a wasteful number, since it uses less digits than its factorization.

21778401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13772 (or 13749 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 30.

The square root of 21778401 is about 4666.7334399985. The cubic root of 21778401 is about 279.2599547835.

The spelling of 21778401 in words is "twenty-one million, seven hundred seventy-eight thousand, four hundred one".