21571090640 has 160 divisors (see below), whose sum is σ = 57700771200. Its totient is φ = 7417128960.

The previous prime is 21571090571. The next prime is 21571090643. The reversal of 21571090640 is 4609017512.

It is a Cunningham number, because it is equal to 146871²-1.

It is a self number, because there is not a number n which added to its sum of digits gives 21571090640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571090643) 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, 12923726 + ... + 12925394.

It is an arithmetic number, because the mean of its divisors is an integer number (360629820).

Almost surely, 2^21571090640 is an apocalyptic number.

21571090640 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 21571090640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28850385600).

21571090640 is an abundant number, since it is smaller than the sum of its proper divisors (36129680560).

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

21571090640 is a wasteful number, since it uses less digits than its factorization.

21571090640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2485 (or 2479 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 35.

The spelling of 21571090640 in words is "twenty-one billion, five hundred seventy-one million, ninety thousand, six hundred forty".