21777225 has 24 divisors (see below), whose sum is σ = 36164352. Its totient is φ = 11563200.

The previous prime is 21777209. The next prime is 21777229. The reversal of 21777225 is 52277712.

It is not a de Polignac number, because 21777225 - 2⁴ = 21777209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21777229) 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 23 ways as a sum of consecutive naturals, for example, 21480 + ... + 22470.

It is an arithmetic number, because the mean of its divisors is an integer number (1506848).

Almost surely, 2^21777225 is an apocalyptic number.

21777225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21777225 is a deficient number, since it is larger than the sum of its proper divisors (14387127).

21777225 is a wasteful number, since it uses less digits than its factorization.

21777225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297 (or 1292 counting only the distinct ones).

The product of its digits is 13720, while the sum is 33.

The square root of 21777225 is about 4666.6074401004. The cubic root of 21777225 is about 279.2549281577.

The spelling of 21777225 in words is "twenty-one million, seven hundred seventy-seven thousand, two hundred twenty-five".