21000020203637 has 2 divisors, whose sum is σ = 21000020203638. Its totient is φ = 21000020203636.

The previous prime is 21000020203621. The next prime is 21000020203777. The reversal of 21000020203637 is 73630202000012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12493616306161 + 8506403897476 = 3534631^2 + 2916574^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000020203637 - 2⁴ = 21000020203621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000020203937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500010101818 + 10500010101819.

It is an arithmetic number, because the mean of its divisors is an integer number (10500010101819).

Almost surely, 2^{21000020203637} is an apocalyptic number.

It is an amenable number.

21000020203637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000020203637 is an equidigital number, since it uses as much as digits as its factorization.

21000020203637 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.

Adding to 21000020203637 its reverse (73630202000012), we get a palindrome (94630222203649).

The spelling of 21000020203637 in words is "twenty-one trillion, twenty million, two hundred three thousand, six hundred thirty-seven".