20505740 has 48 divisors (see below), whose sum is σ = 46738944. Its totient is φ = 7526400.

The previous prime is 20505713. The next prime is 20505761. The reversal of 20505740 is 4750502.

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 15 ways as a sum of consecutive naturals, for example, 13205 + ... + 14675.

It is an arithmetic number, because the mean of its divisors is an integer number (973728).

Almost surely, 2^20505740 is an apocalyptic number.

20505740 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 20505740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23369472).

20505740 is an abundant number, since it is smaller than the sum of its proper divisors (26233204).

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

20505740 is a wasteful number, since it uses less digits than its factorization.

20505740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1538 (or 1536 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 23.

The square root of 20505740 is about 4528.3264016632. The cubic root of 20505740 is about 273.7107253067.

The spelling of 20505740 in words is "twenty million, five hundred five thousand, seven hundred forty".