20071640 has 32 divisors (see below), whose sum is σ = 47126880. Its totient is φ = 7679232.

The previous prime is 20071637. The next prime is 20071643. The reversal of 20071640 is 4617002.

It is an interprime number because it is at equal distance from previous prime (20071637) and next prime (20071643).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20071643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9989 + ... + 11828.

It is an arithmetic number, because the mean of its divisors is an integer number (1472715).

Almost surely, 2^20071640 is an apocalyptic number.

20071640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20071640 is an abundant number, since it is smaller than the sum of its proper divisors (27055240).

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

20071640 is a wasteful number, since it uses less digits than its factorization.

20071640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21851 (or 21847 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 20071640 is about 4480.1383907196. The cubic root of 20071640 is about 271.7654769140.

Adding to 20071640 its reverse (4617002), we get a palindrome (24688642).

The spelling of 20071640 in words is "twenty million, seventy-one thousand, six hundred forty".