20723220 has 72 divisors (see below), whose sum is σ = 71844864. Its totient is φ = 4736448.

The previous prime is 20723173. The next prime is 20723231. The reversal of 20723220 is 2232702.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20723193 and 20723202.

It is a congruent number.

It is an unprimeable number.

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, 6964 + ... + 9483.

Almost surely, 2^20723220 is an apocalyptic number.

20723220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20723220 is an abundant number, since it is smaller than the sum of its proper divisors (51121644).

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

20723220 is a wasteful number, since it uses less digits than its factorization.

20723220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16469 (or 16464 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 18.

The square root of 20723220 is about 4552.2763536499. The cubic root of 20723220 is about 274.6749658420.

Adding to 20723220 its reverse (2232702), we get a palindrome (22955922).

The spelling of 20723220 in words is "twenty million, seven hundred twenty-three thousand, two hundred twenty".