20957440 has 72 divisors (see below), whose sum is σ = 57395520. Its totient is φ = 7182336.

The previous prime is 20957407. The next prime is 20957473. The reversal of 20957440 is 4475902.

It is an interprime number because it is at equal distance from previous prime (20957407) and next prime (20957473).

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a zygodrome in base 8.

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 7 ways as a sum of consecutive naturals, for example, 7791 + ... + 10129.

It is an arithmetic number, because the mean of its divisors is an integer number (797160).

Almost surely, 2^20957440 is an apocalyptic number.

20957440 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 20957440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28697760).

20957440 is an abundant number, since it is smaller than the sum of its proper divisors (36438080).

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

20957440 is an equidigital number, since it uses as much as digits as its factorization.

20957440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2367 (or 2353 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 20957440 is about 4577.9296630682. The cubic root of 20957440 is about 275.7059109302.

The spelling of 20957440 in words is "twenty million, nine hundred fifty-seven thousand, four hundred forty".