21505789129 has 8 divisors (see below), whose sum is σ = 23464836000. Its totient is φ = 19547404800.

The previous prime is 21505789117. The next prime is 21505789183. The reversal of 21505789129 is 92198750512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21505789129 - 2¹⁵ = 21505756361 is a prime.

It is a super-2 number, since 2×21505789129² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21505789189) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96504 + ... + 228745.

It is an arithmetic number, because the mean of its divisors is an integer number (2933104500).

Almost surely, 2^21505789129 is an apocalyptic number.

It is an amenable number.

21505789129 is a deficient number, since it is larger than the sum of its proper divisors (1959046871).

21505789129 is a wasteful number, since it uses less digits than its factorization.

21505789129 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331271.

The product of its (nonzero) digits is 453600, while the sum is 49.

The spelling of 21505789129 in words is "twenty-one billion, five hundred five million, seven hundred eighty-nine thousand, one hundred twenty-nine".