21515189436 has 192 divisors, whose sum is σ = 63470131200. Its totient is φ = 6255228672.

The previous prime is 21515189387. The next prime is 21515189441. The reversal of 21515189436 is 63498151512.

It is a happy number.

21515189436 is a `hidden beast` number, since 2 + 1 + 515 + 18 + 94 + 36 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21515189391 and 21515189400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1908031 + ... + 1919273.

It is an arithmetic number, because the mean of its divisors is an integer number (330573600).

Almost surely, 2^21515189436 is an apocalyptic number.

21515189436 is a gapful number since it is divisible by the number (26) 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 21515189436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31735065600).

21515189436 is an abundant number, since it is smaller than the sum of its proper divisors (41954941764).

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

21515189436 is a wasteful number, since it uses less digits than its factorization.

21515189436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11345 (or 11337 counting only the distinct ones).

The product of its digits is 259200, while the sum is 45.

The spelling of 21515189436 in words is "twenty-one billion, five hundred fifteen million, one hundred eighty-nine thousand, four hundred thirty-six".