21129849531 has 36 divisors (see below), whose sum is σ = 35855496144. Its totient is φ = 11954628000.

The previous prime is 21129849527. The next prime is 21129849557. The reversal of 21129849531 is 13594892112.

21129849531 is a `hidden beast` number, since 2 + 1 + 129 + 8 + 495 + 31 = 666.

It is not a de Polignac number, because 21129849531 - 2² = 21129849527 is a prime.

It is a super-2 number, since 2×21129849531² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21129849131) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 192655 + ... + 281736.

It is an arithmetic number, because the mean of its divisors is an integer number (995986004).

Almost surely, 2^21129849531 is an apocalyptic number.

21129849531 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21129849531 is a deficient number, since it is larger than the sum of its proper divisors (14725646613).

21129849531 is a wasteful number, since it uses less digits than its factorization.

21129849531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474512 (or 474502 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The spelling of 21129849531 in words is "twenty-one billion, one hundred twenty-nine million, eight hundred forty-nine thousand, five hundred thirty-one".