21137781504 has 864 divisors, whose sum is σ = 76503813120. Its totient is φ = 5127929856.

The previous prime is 21137781503. The next prime is 21137781529. The reversal of 21137781504 is 40518773112.

It is a happy number.

It is a super-3 number, since 3×21137781504³ (a number of 32 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21137781503) 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 95 ways as a sum of consecutive naturals, for example, 449740009 + ... + 449740055.

It is an arithmetic number, because the mean of its divisors is an integer number (88546080).

Almost surely, 2^21137781504 is an apocalyptic number.

21137781504 is a gapful number since it is divisible by the number (24) 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 21137781504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38251906560).

21137781504 is an abundant number, since it is smaller than the sum of its proper divisors (55366031616).

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

21137781504 is a wasteful number, since it uses less digits than its factorization.

21137781504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 47040, while the sum is 39.

The spelling of 21137781504 in words is "twenty-one billion, one hundred thirty-seven million, seven hundred eighty-one thousand, five hundred four".