21235427578 has 16 divisors (see below), whose sum is σ = 32638420584. Its totient is φ = 10356087040.

The previous prime is 21235427531. The next prime is 21235427581. The reversal of 21235427578 is 87572453212.

It can be written as a sum of positive squares in 4 ways, for example, as 10567223209 + 10668204369 = 102797^2 + 103287^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 309726 + ... + 372022.

Almost surely, 2^21235427578 is an apocalyptic number.

21235427578 is a deficient number, since it is larger than the sum of its proper divisors (11402993006).

21235427578 is a wasteful number, since it uses less digits than its factorization.

21235427578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66497.

The product of its digits is 940800, while the sum is 46.

It can be divided in two parts, 212354 and 27578, that added together give a palindrome (239932).

The spelling of 21235427578 in words is "twenty-one billion, two hundred thirty-five million, four hundred twenty-seven thousand, five hundred seventy-eight".