21222772 has 24 divisors (see below), whose sum is σ = 39765600. Its totient is φ = 9880416.

The previous prime is 21222757. The next prime is 21222787. The reversal of 21222772 is 27722212.

It is an interprime number because it is at equal distance from previous prime (21222757) and next prime (21222787).

It is a super-4 number, since 4×21222772⁴ (a number of 30 digits) contains 4444 as substring.

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, 2118 + ... + 6850.

It is an arithmetic number, because the mean of its divisors is an integer number (1656900).

Almost surely, 2^21222772 is an apocalyptic number.

It is an amenable number.

21222772 is a deficient number, since it is larger than the sum of its proper divisors (18542828).

21222772 is a wasteful number, since it uses less digits than its factorization.

21222772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4815 (or 4813 counting only the distinct ones).

The product of its digits is 1568, while the sum is 25.

The square root of 21222772 is about 4606.8179907611. The cubic root of 21222772 is about 276.8645612433.

Adding to 21222772 its reverse (27722212), we get a palindrome (48944984).

The spelling of 21222772 in words is "twenty-one million, two hundred twenty-two thousand, seven hundred seventy-two".