21997593500 has 48 divisors (see below), whose sum is σ = 48154684032. Its totient is φ = 8778536000.

The previous prime is 21997593487. The next prime is 21997593509. The reversal of 21997593500 is 539579912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (50).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21997593509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 164462 + ... + 266538.

It is an arithmetic number, because the mean of its divisors is an integer number (1003222584).

Almost surely, 2^21997593500 is an apocalyptic number.

21997593500 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 21997593500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24077342016).

21997593500 is an abundant number, since it is smaller than the sum of its proper divisors (26157090532).

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

21997593500 is a wasteful number, since it uses less digits than its factorization.

21997593500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102527 (or 102515 counting only the distinct ones).

The product of its (nonzero) digits is 765450, while the sum is 50.

The spelling of 21997593500 in words is "twenty-one billion, nine hundred ninety-seven million, five hundred ninety-three thousand, five hundred".