21530571909 has 32 divisors (see below), whose sum is σ = 35812399104. Its totient is φ = 11178050880.

The previous prime is 21530571901. The next prime is 21530571973. The reversal of 21530571909 is 90917503512.

It is not a de Polignac number, because 21530571909 - 2³ = 21530571901 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530571901) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 373432 + ... + 427214.

It is an arithmetic number, because the mean of its divisors is an integer number (1119137472).

Almost surely, 2^21530571909 is an apocalyptic number.

It is an amenable number.

21530571909 is a deficient number, since it is larger than the sum of its proper divisors (14281827195).

21530571909 is a wasteful number, since it uses less digits than its factorization.

21530571909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55537.

The product of its (nonzero) digits is 85050, while the sum is 42.

The spelling of 21530571909 in words is "twenty-one billion, five hundred thirty million, five hundred seventy-one thousand, nine hundred nine".