21291033744 has 30 divisors (see below), whose sum is σ = 59585324006. Its totient is φ = 7097011200.

The previous prime is 21291033719. The next prime is 21291033749. The reversal of 21291033744 is 44733019212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17427168144 + 3863865600 = 132012^2 + 62160^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21291033699 and 21291033708.

It is not an unprimeable number, because it can be changed into a prime (21291033749) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 73927057 + ... + 73927344.

Almost surely, 2^21291033744 is an apocalyptic number.

21291033744 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21291033744 is an abundant number, since it is smaller than the sum of its proper divisors (38294290262).

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

21291033744 is a wasteful number, since it uses less digits than its factorization.

21291033744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147854415 (or 147854406 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The spelling of 21291033744 in words is "twenty-one billion, two hundred ninety-one million, thirty-three thousand, seven hundred forty-four".