20651381 has 2 divisors, whose sum is σ = 20651382. Its totient is φ = 20651380.

The previous prime is 20651353. The next prime is 20651419. The reversal of 20651381 is 18315602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18062500 + 2588881 = 4250^2 + 1609^2 .

It is a cyclic number.

It is not a de Polignac number, because 20651381 - 2⁶ = 20651317 is a prime.

It is a super-2 number, since 2×20651381² = 852959074414322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20651381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20651341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10325690 + 10325691.

It is an arithmetic number, because the mean of its divisors is an integer number (10325691).

Almost surely, 2^20651381 is an apocalyptic number.

It is an amenable number.

20651381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20651381 is an equidigital number, since it uses as much as digits as its factorization.

20651381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 20651381 is about 4544.3790554926. The cubic root of 20651381 is about 274.3572028002.

Adding to 20651381 its reverse (18315602), we get a palindrome (38966983).

The spelling of 20651381 in words is "twenty million, six hundred fifty-one thousand, three hundred eighty-one".