21497340721944 has 128 divisors (see below), whose sum is σ = 57328359379200. Its totient is φ = 6694079447040.

The previous prime is 21497340721873. The next prime is 21497340721979. The reversal of 21497340721944 is 44912704379412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 238769224 + ... + 238859240.

It is an arithmetic number, because the mean of its divisors is an integer number (447877807650).

Almost surely, 2^{21497340721944} is an apocalyptic number.

21497340721944 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 21497340721944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28664179689600).

21497340721944 is an abundant number, since it is smaller than the sum of its proper divisors (35831018657256).

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

21497340721944 is a wasteful number, since it uses less digits than its factorization.

21497340721944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94393 (or 94389 counting only the distinct ones).

The product of its (nonzero) digits is 12192768, while the sum is 57.

The spelling of 21497340721944 in words is "twenty-one trillion, four hundred ninety-seven billion, three hundred forty million, seven hundred twenty-one thousand, nine hundred forty-four".