21198843637 has 2 divisors, whose sum is σ = 21198843638. Its totient is φ = 21198843636.

The previous prime is 21198843587. The next prime is 21198843649. The reversal of 21198843637 is 73634889112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19880718001 + 1318125636 = 140999^2 + 36306^2 .

It is a cyclic number.

It is not a de Polignac number, because 21198843637 - 2⁷ = 21198843509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21198843667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10599421818 + 10599421819.

It is an arithmetic number, because the mean of its divisors is an integer number (10599421819).

Almost surely, 2^21198843637 is an apocalyptic number.

It is an amenable number.

21198843637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21198843637 is an equidigital number, since it uses as much as digits as its factorization.

21198843637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1741824, while the sum is 52.

The spelling of 21198843637 in words is "twenty-one billion, one hundred ninety-eight million, eight hundred forty-three thousand, six hundred thirty-seven".