21275217637 has 4 divisors (see below), whose sum is σ = 21276769696. Its totient is φ = 21273665580.

The previous prime is 21275217617. The next prime is 21275217703. The reversal of 21275217637 is 73671257212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21275217637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21275217593 and 21275217602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21275217617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 755283 + ... + 782944.

It is an arithmetic number, because the mean of its divisors is an integer number (5319192424).

Almost surely, 2^21275217637 is an apocalyptic number.

It is an amenable number.

21275217637 is a deficient number, since it is larger than the sum of its proper divisors (1552059).

21275217637 is a wasteful number, since it uses less digits than its factorization.

21275217637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1552058.

The product of its digits is 246960, while the sum is 43.

The spelling of 21275217637 in words is "twenty-one billion, two hundred seventy-five million, two hundred seventeen thousand, six hundred thirty-seven".