21511523140 has 96 divisors (see below), whose sum is σ = 47948060160. Its totient is φ = 8092761600.

The previous prime is 21511523083. The next prime is 21511523141. The reversal of 21511523140 is 4132511512.

It is not an unprimeable number, because it can be changed into a prime (21511523141) 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, 11496405 + ... + 11498275.

It is an arithmetic number, because the mean of its divisors is an integer number (499458960).

Almost surely, 2^21511523140 is an apocalyptic number.

21511523140 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 21511523140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23974030080).

21511523140 is an abundant number, since it is smaller than the sum of its proper divisors (26436537020).

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

21511523140 is a wasteful number, since it uses less digits than its factorization.

21511523140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2413 (or 2411 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 25.

The spelling of 21511523140 in words is "twenty-one billion, five hundred eleven million, five hundred twenty-three thousand, one hundred forty".