21243431000 has 128 divisors (see below), whose sum is σ = 54768467520. Its totient is φ = 7648000000.

The previous prime is 21243430991. The next prime is 21243431017. The reversal of 21243431000 is 13434212.

It is a super-2 number, since 2×21243431000² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1101440 + ... + 1120560.

Almost surely, 2^21243431000 is an apocalyptic number.

21243431000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21243431000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27384233760).

21243431000 is an abundant number, since it is smaller than the sum of its proper divisors (33525036520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21243431000 is a wasteful number, since it uses less digits than its factorization.

21243431000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19254 (or 19240 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21243431000 its reverse (13434212), we get a palindrome (21256865212).

The spelling of 21243431000 in words is "twenty-one billion, two hundred forty-three million, four hundred thirty-one thousand".