20009640 has 192 divisors, whose sum is σ = 72394560. Its totient is φ = 4408320.

The previous prime is 20009611. The next prime is 20009651. The reversal of 20009640 is 4690002.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 241039 + ... + 241121.

It is an arithmetic number, because the mean of its divisors is an integer number (377055).

Almost surely, 2^20009640 is an apocalyptic number.

20009640 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 20009640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36197280).

20009640 is an abundant number, since it is smaller than the sum of its proper divisors (52384920).

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

20009640 is a wasteful number, since it uses less digits than its factorization.

20009640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20009640 is about 4473.2136099230. The cubic root of 20009640 is about 271.4853662975.

Adding to 20009640 its reverse (4690002), we get a palindrome (24699642).

The spelling of 20009640 in words is "twenty million, nine thousand, six hundred forty".