28178021773 has 6 divisors (see below), whose sum is σ = 30972536462. Its totient is φ = 25616383320.

The previous prime is 28178021771. The next prime is 28178021777. The reversal of 28178021773 is 37712087182.

It can be written as a sum of positive squares in only one way, i.e., 22571456644 + 5606565129 = 150238^2 + 74877^2 .

It is not a de Polignac number, because 28178021773 - 2¹ = 28178021771 is a prime.

It is a super-2 number, since 2×28178021773² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28178021771) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 116437986 + ... + 116438227.

Almost surely, 2^28178021773 is an apocalyptic number.

It is an amenable number.

28178021773 is a deficient number, since it is larger than the sum of its proper divisors (2794514689).

28178021773 is a wasteful number, since it uses less digits than its factorization.

28178021773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232876235 (or 232876224 counting only the distinct ones).

The product of its (nonzero) digits is 263424, while the sum is 46.

The spelling of 28178021773 in words is "twenty-eight billion, one hundred seventy-eight million, twenty-one thousand, seven hundred seventy-three".