20681428 has 6 divisors (see below), whose sum is σ = 36192506. Its totient is φ = 10340712.

The previous prime is 20681407. The next prime is 20681449. The reversal of 20681428 is 82418602.

It is an interprime number because it is at equal distance from previous prime (20681407) and next prime (20681449).

It can be written as a sum of positive squares in only one way, i.e., 10771524 + 9909904 = 3282^2 + 3148^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20681428.

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 as a sum of consecutive naturals, namely, 2585175 + ... + 2585182.

Almost surely, 2^20681428 is an apocalyptic number.

It is an amenable number.

20681428 is a deficient number, since it is larger than the sum of its proper divisors (15511078).

20681428 is a wasteful number, since it uses less digits than its factorization.

20681428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5170361 (or 5170359 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 31.

The square root of 20681428 is about 4547.6838060710. The cubic root of 20681428 is about 274.4901982005.

The spelling of 20681428 in words is "twenty million, six hundred eighty-one thousand, four hundred twenty-eight".