21778801 has 4 divisors (see below), whose sum is σ = 23758704. Its totient is φ = 19798900.

The previous prime is 21778793. The next prime is 21778811. The reversal of 21778801 is 10887712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21778801 - 2³ = 21778793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21778811) 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 3 ways as a sum of consecutive naturals, for example, 989935 + ... + 989956.

It is an arithmetic number, because the mean of its divisors is an integer number (5939676).

Almost surely, 2^21778801 is an apocalyptic number.

It is an amenable number.

21778801 is a deficient number, since it is larger than the sum of its proper divisors (1979903).

21778801 is a wasteful number, since it uses less digits than its factorization.

21778801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1979902.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 21778801 is about 4666.7762963313. The cubic root of 21778801 is about 279.2616644789.

The spelling of 21778801 in words is "twenty-one million, seven hundred seventy-eight thousand, eight hundred one".