20643240 has 32 divisors (see below), whose sum is σ = 61930080. Its totient is φ = 5504832.

The previous prime is 20643239. The next prime is 20643251. The reversal of 20643240 is 4234602.

It is a super-2 number, since 2×20643240² = 852286715395200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85894 + ... + 86133.

It is an arithmetic number, because the mean of its divisors is an integer number (1935315).

Almost surely, 2^20643240 is an apocalyptic number.

20643240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20643240 is an abundant number, since it is smaller than the sum of its proper divisors (41286840).

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

20643240 is a wasteful number, since it uses less digits than its factorization.

20643240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172041 (or 172037 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 20643240 is about 4543.4832452646. The cubic root of 20643240 is about 274.3211465263.

Adding to 20643240 its reverse (4234602), we get a palindrome (24877842).

The spelling of 20643240 in words is "twenty million, six hundred forty-three thousand, two hundred forty".