21375172117640 has 128 divisors (see below), whose sum is σ = 53585970577920. Its totient is φ = 7606938009600.

The previous prime is 21375172117627. The next prime is 21375172117643. The reversal of 21375172117640 is 4671127157312.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is not an unprimeable number, because it can be changed into a prime (21375172117643) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 651010664 + ... + 651043496.

It is an arithmetic number, because the mean of its divisors is an integer number (418640395140).

Almost surely, 2^{21375172117640} is an apocalyptic number.

21375172117640 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 21375172117640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26792985288960).

21375172117640 is an abundant number, since it is smaller than the sum of its proper divisors (32210798460280).

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

21375172117640 is a wasteful number, since it uses less digits than its factorization.

21375172117640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64383 (or 64379 counting only the distinct ones).

The product of its (nonzero) digits is 493920, while the sum is 47.

The spelling of 21375172117640 in words is "twenty-one trillion, three hundred seventy-five billion, one hundred seventy-two million, one hundred seventeen thousand, six hundred forty".