20781338 has 4 divisors (see below), whose sum is σ = 31172010. Its totient is φ = 10390668.

The previous prime is 20781337. The next prime is 20781349. The reversal of 20781338 is 83318702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 51529 = 4553^2 + 227^2 .

It is not an unprimeable number, because it can be changed into a prime (20781337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5195333 + ... + 5195336.

Almost surely, 2^20781338 is an apocalyptic number.

20781338 is a deficient number, since it is larger than the sum of its proper divisors (10390672).

20781338 is a wasteful number, since it uses less digits than its factorization.

20781338 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10390671.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20781338 is about 4558.6552841819. The cubic root of 20781338 is about 274.9315002942.

The spelling of 20781338 in words is "twenty million, seven hundred eighty-one thousand, three hundred thirty-eight".