21772780 has 12 divisors (see below), whose sum is σ = 45722880. Its totient is φ = 8709104.

The previous prime is 21772769. The next prime is 21772787. The reversal of 21772780 is 8727712.

It is not an unprimeable number, because it can be changed into a prime (21772787) 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 3 ways as a sum of consecutive naturals, for example, 544300 + ... + 544339.

It is an arithmetic number, because the mean of its divisors is an integer number (3810240).

Almost surely, 2^21772780 is an apocalyptic number.

21772780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21772780 is an abundant number, since it is smaller than the sum of its proper divisors (23950100).

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

21772780 is a wasteful number, since it uses less digits than its factorization.

21772780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1088648 (or 1088646 counting only the distinct ones).

The product of its (nonzero) digits is 10976, while the sum is 34.

The square root of 21772780 is about 4666.1311597511. The cubic root of 21772780 is about 279.2359270741.

The spelling of 21772780 in words is "twenty-one million, seven hundred seventy-two thousand, seven hundred eighty".