21772020 has 24 divisors (see below), whose sum is σ = 60961824. Its totient is φ = 5805856.

The previous prime is 21772001. The next prime is 21772033. The reversal of 21772020 is 2027712.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 181374 + ... + 181493.

It is an arithmetic number, because the mean of its divisors is an integer number (2540076).

Almost surely, 2^21772020 is an apocalyptic number.

21772020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21772020 is an abundant number, since it is smaller than the sum of its proper divisors (39189804).

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

21772020 is a wasteful number, since it uses less digits than its factorization.

21772020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362879 (or 362877 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 21.

The square root of 21772020 is about 4666.0497211239. The cubic root of 21772020 is about 279.2326780360.

Adding to 21772020 its reverse (2027712), we get a palindrome (23799732).

The spelling of 21772020 in words is "twenty-one million, seven hundred seventy-two thousand, twenty".