21206058129 has 9 divisors (see below), whose sum is σ = 30631603899. Its totient is φ = 14137080840.

The previous prime is 21206058109. The next prime is 21206058143. The reversal of 21206058129 is 92185060212.

The square root of 21206058129 is 145623.

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

21206058129 is a `hidden beast` number, since 2 + 1 + 20 + 605 + 8 + 1 + 29 = 666.

It can be written as a sum of positive squares in only one way, i.e., 314246529 + 20891811600 = 17727^2 + 144540^2 .

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

It is not a de Polignac number, because 21206058129 - 2⁹ = 21206057617 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21206058093 and 21206058102.

It is not an unprimeable number, because it can be changed into a prime (21206058109) 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, 412599 + ... + 461139.

Almost surely, 2^21206058129 is an apocalyptic number.

21206058129 is the 145623-rd square number.

21206058129 is the 72812-nd centered octagonal number.

It is an amenable number.

21206058129 is a deficient number, since it is larger than the sum of its proper divisors (9425545770).

21206058129 is an frugal number, since it uses more digits than its factorization.

21206058129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97088 (or 48544 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

Multiplying 21206058129 by its sum of digits (36), we get a square (763418092644 = 873738²).

The spelling of 21206058129 in words is "twenty-one billion, two hundred six million, fifty-eight thousand, one hundred twenty-nine".