21106513237 has 2 divisors, whose sum is σ = 21106513238. Its totient is φ = 21106513236.

The previous prime is 21106513189. The next prime is 21106513271. The reversal of 21106513237 is 73231560112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12877483441 + 8229029796 = 113479^2 + 90714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21106513237 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21106513199 and 21106513208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21106513537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553256618 + 10553256619.

It is an arithmetic number, because the mean of its divisors is an integer number (10553256619).

Almost surely, 2^21106513237 is an apocalyptic number.

It is an amenable number.

21106513237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106513237 is an equidigital number, since it uses as much as digits as its factorization.

21106513237 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The spelling of 21106513237 in words is "twenty-one billion, one hundred six million, five hundred thirteen thousand, two hundred thirty-seven".