21106513537 has 2 divisors, whose sum is σ = 21106513538. Its totient is φ = 21106513536.

The previous prime is 21106513529. The next prime is 21106513541. The reversal of 21106513537 is 73531560112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15725410801 + 5381102736 = 125401^2 + 73356^2 .

It is a cyclic number.

It is not a de Polignac number, because 21106513537 - 2³ = 21106513529 is a prime.

It is not a weakly prime, because it can be changed into another prime (21106513517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553256768 + 10553256769.

It is an arithmetic number, because the mean of its divisors is an integer number (10553256769).

Almost surely, 2^21106513537 is an apocalyptic number.

It is an amenable number.

21106513537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106513537 is an equidigital number, since it uses as much as digits as its factorization.

21106513537 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18900, while the sum is 34.

The spelling of 21106513537 in words is "twenty-one billion, one hundred six million, five hundred thirteen thousand, five hundred thirty-seven".