20642440 has 128 divisors (see below), whose sum is σ = 58786560. Its totient is φ = 6349824.

The previous prime is 20642423. The next prime is 20642443. The reversal of 20642440 is 4424602.

It is a super-2 number, since 2×20642440² = 852220658307200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20642443) 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 31 ways as a sum of consecutive naturals, for example, 192867 + ... + 192973.

It is an arithmetic number, because the mean of its divisors is an integer number (459270).

Almost surely, 2^20642440 is an apocalyptic number.

20642440 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 20642440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29393280).

20642440 is an abundant number, since it is smaller than the sum of its proper divisors (38144120).

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

20642440 is a wasteful number, since it uses less digits than its factorization.

20642440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191 (or 187 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 20642440 is about 4543.3952062307. The cubic root of 20642440 is about 274.3176028360.

The spelling of 20642440 in words is "twenty million, six hundred forty-two thousand, four hundred forty".