20406720 has 112 divisors (see below), whose sum is σ = 67116960. Its totient is φ = 5246976.

The previous prime is 20406697. The next prime is 20406767. The reversal of 20406720 is 2760402.

It is a happy number.

It is a super-3 number, since 3×20406720³ (a number of 23 digits) contains 333 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 (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27474 + ... + 28206.

Almost surely, 2^20406720 is an apocalyptic number.

20406720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20406720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33558480).

20406720 is an abundant number, since it is smaller than the sum of its proper divisors (46710240).

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

20406720 is a wasteful number, since it uses less digits than its factorization.

20406720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 782 (or 772 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 20406720 is about 4517.3797715047. The cubic root of 20406720 is about 273.2694410778.

The spelling of 20406720 in words is "twenty million, four hundred six thousand, seven hundred twenty".