21520107408 has 80 divisors (see below), whose sum is σ = 58771327680. Its totient is φ = 6766589952.

The previous prime is 21520107337. The next prime is 21520107409. The reversal of 21520107408 is 80470102512.

It is not an unprimeable number, because it can be changed into a prime (21520107409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 161860 + ... + 263132.

It is an arithmetic number, because the mean of its divisors is an integer number (734641596).

Almost surely, 2^21520107408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21520107408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29385663840).

21520107408 is an abundant number, since it is smaller than the sum of its proper divisors (37251220272).

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

21520107408 is a wasteful number, since it uses less digits than its factorization.

21520107408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101536 (or 101530 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 30.

The spelling of 21520107408 in words is "twenty-one billion, five hundred twenty million, one hundred seven thousand, four hundred eight".