20781340 has 12 divisors (see below), whose sum is σ = 43640856. Its totient is φ = 8312528.

The previous prime is 20781337. The next prime is 20781349. The reversal of 20781340 is 4318702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20781349) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 519514 + ... + 519553.

It is an arithmetic number, because the mean of its divisors is an integer number (3636738).

Almost surely, 2^20781340 is an apocalyptic number.

20781340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20781340 is an abundant number, since it is smaller than the sum of its proper divisors (22859516).

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

20781340 is a wasteful number, since it uses less digits than its factorization.

20781340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1039076 (or 1039074 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 20781340 is about 4558.6555035449. The cubic root of 20781340 is about 274.9315091140.

The spelling of 20781340 in words is "twenty million, seven hundred eighty-one thousand, three hundred forty".