21871156321 has 27 divisors (see below), whose sum is σ = 26194035987. Its totient is φ = 18208093680.

The previous prime is 21871156277. The next prime is 21871156339. The reversal of 21871156321 is 12365117812.

The square root of 21871156321 is 147889.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 19570611025 + 2300545296 = 139895^2 + 47964^2 .

It is not a de Polignac number, because 21871156321 - 2¹⁹ = 21870632033 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (21871156361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 38302966 + ... + 38303536.

It is an arithmetic number, because the mean of its divisors is an integer number (970149481).

Almost surely, 2^21871156321 is an apocalyptic number.

21871156321 is the 147889-th square number.

21871156321 is the 73945-th centered octagonal number.

It is an amenable number.

21871156321 is a deficient number, since it is larger than the sum of its proper divisors (4322879666).

21871156321 is an frugal number, since it uses more digits than its factorization.

21871156321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1230 (or 615 counting only the distinct ones).

The product of its digits is 20160, while the sum is 37.

The spelling of 21871156321 in words is "twenty-one billion, eight hundred seventy-one million, one hundred fifty-six thousand, three hundred twenty-one".