21138934500 has 288 divisors, whose sum is σ = 72803902080. Its totient is φ = 5339779200.

The previous prime is 21138934499. The next prime is 21138934501. The reversal of 21138934500 is 543983112.

21138934500 is a `hidden beast` number, since 2 + 113 + 8 + 9 + 34 + 500 = 666.

It is an interprime number because it is at equal distance from previous prime (21138934499) and next prime (21138934501).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21138934501) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2303922 + ... + 2313078.

Almost surely, 2^21138934500 is an apocalyptic number.

21138934500 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 21138934500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36401951040).

21138934500 is an abundant number, since it is smaller than the sum of its proper divisors (51664967580).

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

21138934500 is a wasteful number, since it uses less digits than its factorization.

21138934500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9210 (or 9186 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The spelling of 21138934500 in words is "twenty-one billion, one hundred thirty-eight million, nine hundred thirty-four thousand, five hundred".