21757878172 has 12 divisors (see below), whose sum is σ = 38331833400. Its totient is φ = 10805925776.

The previous prime is 21757878143. The next prime is 21757878203. The reversal of 21757878172 is 27187875712.

It is a super-3 number, since 3×21757878172³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18252658 + ... + 18253849.

It is an arithmetic number, because the mean of its divisors is an integer number (3194319450).

Almost surely, 2^21757878172 is an apocalyptic number.

It is an amenable number.

21757878172 is a deficient number, since it is larger than the sum of its proper divisors (16573955228).

21757878172 is a wasteful number, since it uses less digits than its factorization.

21757878172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36506660 (or 36506658 counting only the distinct ones).

The product of its digits is 3073280, while the sum is 55.

The spelling of 21757878172 in words is "twenty-one billion, seven hundred fifty-seven million, eight hundred seventy-eight thousand, one hundred seventy-two".