21715361388 has 96 divisors (see below), whose sum is σ = 64736913920. Its totient is φ = 6166290240.

The previous prime is 21715361363. The next prime is 21715361389. The reversal of 21715361388 is 88316351712.

It is a happy number.

21715361388 is a `hidden beast` number, since 2 + 17 + 15 + 3 + 613 + 8 + 8 = 666.

It is a super-2 number, since 2×21715361388² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21715361389) 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 31 ways as a sum of consecutive naturals, for example, 35118 + ... + 211338.

Almost surely, 2^21715361388 is an apocalyptic number.

21715361388 is a gapful number since it is divisible by the number (28) 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 21715361388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32368456960).

21715361388 is an abundant number, since it is smaller than the sum of its proper divisors (43021552532).

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

21715361388 is a wasteful number, since it uses less digits than its factorization.

21715361388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176404 (or 176396 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The spelling of 21715361388 in words is "twenty-one billion, seven hundred fifteen million, three hundred sixty-one thousand, three hundred eighty-eight".