21872278644 has 48 divisors (see below), whose sum is σ = 51541019712. Its totient is φ = 7218652672.

The previous prime is 21872278643. The next prime is 21872278667. The reversal of 21872278644 is 44687227812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21872278643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1365667 + ... + 1381589.

It is an arithmetic number, because the mean of its divisors is an integer number (1073771244).

Almost surely, 2^21872278644 is an apocalyptic number.

It is an amenable number.

21872278644 is an abundant number, since it is smaller than the sum of its proper divisors (29668741068).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21872278644 is a wasteful number, since it uses less digits than its factorization.

21872278644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17056 (or 17054 counting only the distinct ones).

The product of its digits is 2408448, while the sum is 51.

The spelling of 21872278644 in words is "twenty-one billion, eight hundred seventy-two million, two hundred seventy-eight thousand, six hundred forty-four".