20643137 has 2 divisors, whose sum is σ = 20643138. Its totient is φ = 20643136.

The previous prime is 20643127. The next prime is 20643143. The reversal of 20643137 is 73134602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16679056 + 3964081 = 4084^2 + 1991^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20643137 is a prime.

It is a super-2 number, since 2×20643137² = 852278210401538, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20643107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10321568 + 10321569.

It is an arithmetic number, because the mean of its divisors is an integer number (10321569).

Almost surely, 2^20643137 is an apocalyptic number.

It is an amenable number.

20643137 is a deficient number, since it is larger than the sum of its proper divisors (1).

20643137 is an equidigital number, since it uses as much as digits as its factorization.

20643137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 26.

The square root of 20643137 is about 4543.4719103347. The cubic root of 20643137 is about 274.3206902813.

Adding to 20643137 its reverse (73134602), we get a palindrome (93777739).

The spelling of 20643137 in words is "twenty million, six hundred forty-three thousand, one hundred thirty-seven".