21955637537 has 2 divisors, whose sum is σ = 21955637538. Its totient is φ = 21955637536.

The previous prime is 21955637507. The next prime is 21955637611. The reversal of 21955637537 is 73573655912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15634751521 + 6320886016 = 125039^2 + 79504^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21955637537 is a prime.

It is a super-2 number, since 2×21955637537² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21955637507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10977818768 + 10977818769.

It is an arithmetic number, because the mean of its divisors is an integer number (10977818769).

Almost surely, 2^21955637537 is an apocalyptic number.

It is an amenable number.

21955637537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21955637537 is an equidigital number, since it uses as much as digits as its factorization.

21955637537 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5953500, while the sum is 53.

The spelling of 21955637537 in words is "twenty-one billion, nine hundred fifty-five million, six hundred thirty-seven thousand, five hundred thirty-seven".