21507178190840 has 128 divisors (see below), whose sum is σ = 50560981470720. Its totient is φ = 8224501708800.

The previous prime is 21507178190737. The next prime is 21507178190879. The reversal of 21507178190840 is 4809187170512.

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, 33360350 + ... + 33998930.

It is an arithmetic number, because the mean of its divisors is an integer number (395007667740).

Almost surely, 2^{21507178190840} is an apocalyptic number.

21507178190840 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 21507178190840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25280490735360).

21507178190840 is an abundant number, since it is smaller than the sum of its proper divisors (29053803279880).

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

21507178190840 is a wasteful number, since it uses less digits than its factorization.

21507178190840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 638953 (or 638949 counting only the distinct ones).

The product of its (nonzero) digits is 1128960, while the sum is 53.

The spelling of 21507178190840 in words is "twenty-one trillion, five hundred seven billion, one hundred seventy-eight million, one hundred ninety thousand, eight hundred forty".