21512829660 has 384 divisors, whose sum is σ = 74937139200. Its totient is φ = 4598592768.

The previous prime is 21512829649. The next prime is 21512829661. The reversal of 21512829660 is 6692821512.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512829661) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 22246497 + ... + 22247463.

It is an arithmetic number, because the mean of its divisors is an integer number (195148800).

Almost surely, 2^21512829660 is an apocalyptic number.

21512829660 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 21512829660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37468569600).

21512829660 is an abundant number, since it is smaller than the sum of its proper divisors (53424309540).

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

21512829660 is a wasteful number, since it uses less digits than its factorization.

21512829660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1070 (or 1054 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 42.

The spelling of 21512829660 in words is "twenty-one billion, five hundred twelve million, eight hundred twenty-nine thousand, six hundred sixty".