21106170637 has 4 divisors (see below), whose sum is σ = 21299805340. Its totient is φ = 20912535936.

The previous prime is 21106170629. The next prime is 21106170647. The reversal of 21106170637 is 73607160112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9240207876 + 11865962761 = 96126^2 + 108931^2 .

It is a cyclic number.

It is not a de Polignac number, because 21106170637 - 2³ = 21106170629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21106170647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96817188 + ... + 96817405.

It is an arithmetic number, because the mean of its divisors is an integer number (5324951335).

Almost surely, 2^21106170637 is an apocalyptic number.

It is an amenable number.

21106170637 is a deficient number, since it is larger than the sum of its proper divisors (193634703).

21106170637 is a wasteful number, since it uses less digits than its factorization.

21106170637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193634702.

The product of its (nonzero) digits is 10584, while the sum is 34.

The spelling of 21106170637 in words is "twenty-one billion, one hundred six million, one hundred seventy thousand, six hundred thirty-seven".