21778272 has 36 divisors (see below), whose sum is σ = 61932780. Its totient is φ = 7259328.

The previous prime is 21778271. The next prime is 21778279. The reversal of 21778272 is 27287712.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778271) 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 5 ways as a sum of consecutive naturals, for example, 37522 + ... + 38097.

It is an arithmetic number, because the mean of its divisors is an integer number (1720355).

Almost surely, 2^21778272 is an apocalyptic number.

It is an amenable number.

21778272 is an abundant number, since it is smaller than the sum of its proper divisors (40154508).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21778272 is a wasteful number, since it uses less digits than its factorization.

21778272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75635 (or 75624 counting only the distinct ones).

The product of its digits is 21952, while the sum is 36.

The square root of 21778272 is about 4666.7196187472. The cubic root of 21778272 is about 279.2594034023.

The spelling of 21778272 in words is "twenty-one million, seven hundred seventy-eight thousand, two hundred seventy-two".