20781438 has 8 divisors (see below), whose sum is σ = 41562888. Its totient is φ = 6927144.

The previous prime is 20781437. The next prime is 20781451. The reversal of 20781438 is 83418702.

It is a sphenic number, since it is the product of 3 distinct primes.

20781438 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 20781399 and 20781408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20781437) 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, 1731781 + ... + 1731792.

It is an arithmetic number, because the mean of its divisors is an integer number (5195361).

Almost surely, 2^20781438 is an apocalyptic number.

20781438 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

20781438 is a wasteful number, since it uses less digits than its factorization.

20781438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3463578.

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 20781438 is about 4558.6662523155. Note that the first 3 decimals coincide. The cubic root of 20781438 is about 274.9319412845.

The spelling of 20781438 in words is "twenty million, seven hundred eighty-one thousand, four hundred thirty-eight".