21723757637 has 2 divisors, whose sum is σ = 21723757638. Its totient is φ = 21723757636.

The previous prime is 21723757613. The next prime is 21723757667. The reversal of 21723757637 is 73675732712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19447418116 + 2276339521 = 139454^2 + 47711^2 .

It is a cyclic number.

It is not a de Polignac number, because 21723757637 - 2¹⁶ = 21723692101 is a prime.

It is a super-2 number, since 2×21723757637² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21723757667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861878818 + 10861878819.

It is an arithmetic number, because the mean of its divisors is an integer number (10861878819).

Almost surely, 2^21723757637 is an apocalyptic number.

It is an amenable number.

21723757637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21723757637 is an equidigital number, since it uses as much as digits as its factorization.

21723757637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2593080, while the sum is 50.

The spelling of 21723757637 in words is "twenty-one billion, seven hundred twenty-three million, seven hundred fifty-seven thousand, six hundred thirty-seven".