21971243529 has 9 divisors (see below), whose sum is σ = 31736882983. Its totient is φ = 14647199232.

The previous prime is 21971243509. The next prime is 21971243543. The reversal of 21971243529 is 92534217912.

The square root of 21971243529 is 148227.

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

21971243529 is a `hidden beast` number, since 2 + 19 + 71 + 2 + 43 + 529 = 666.

It can be written as a sum of positive squares in only one way, i.e., 8422283529 + 13548960000 = 91773^2 + 116400^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 21971243529 - 2¹⁵ = 21971210761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21971243509) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 419977 + ... + 469385.

Almost surely, 2^21971243529 is an apocalyptic number.

21971243529 is the 148227-th square number.

21971243529 is the 74114-th centered octagonal number.

It is an amenable number.

21971243529 is a deficient number, since it is larger than the sum of its proper divisors (9765639454).

21971243529 is an frugal number, since it uses more digits than its factorization.

21971243529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98824 (or 49412 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The spelling of 21971243529 in words is "twenty-one billion, nine hundred seventy-one million, two hundred forty-three thousand, five hundred twenty-nine".