28190978649538 has 4 divisors (see below), whose sum is σ = 42286467974310. Its totient is φ = 14095489324768.

The previous prime is 28190978649527. The next prime is 28190978649569. The reversal of 28190978649538 is 83594687909182.

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

It can be written as a sum of positive squares in only one way, i.e., 21292807334569 + 6898171314969 = 4614413^2 + 2626437^2 .

It is a super-2 number, since 2×28190978649538² (a number of 28 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7047744662383 + ... + 7047744662386.

It is a 1-persistent number, because it is pandigital, but 2⋅28190978649538 = 56381957299076 is not.

Almost surely, 2^{28190978649538} is an apocalyptic number.

28190978649538 is a deficient number, since it is larger than the sum of its proper divisors (14095489324772).

28190978649538 is a wasteful number, since it uses less digits than its factorization.

28190978649538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14095489324771.

The product of its (nonzero) digits is 1881169920, while the sum is 79.

The spelling of 28190978649538 in words is "twenty-eight trillion, one hundred ninety billion, nine hundred seventy-eight million, six hundred forty-nine thousand, five hundred thirty-eight".