20957720 has 96 divisors (see below), whose sum is σ = 56440800. Its totient is φ = 6859776.

The previous prime is 20957711. The next prime is 20957731. The reversal of 20957720 is 2775902.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 235436 + ... + 235524.

It is an arithmetic number, because the mean of its divisors is an integer number (587925).

Almost surely, 2^20957720 is an apocalyptic number.

20957720 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 20957720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28220400).

20957720 is an abundant number, since it is smaller than the sum of its proper divisors (35483080).

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

20957720 is a wasteful number, since it uses less digits than its factorization.

20957720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 8820, while the sum is 32.

The square root of 20957720 is about 4577.9602444757. The cubic root of 20957720 is about 275.7071387728.

The spelling of 20957720 in words is "twenty million, nine hundred fifty-seven thousand, seven hundred twenty".