21520814408 has 32 divisors (see below), whose sum is σ = 41375040960. Its totient is φ = 10488502080.

The previous prime is 21520814377. The next prime is 21520814423. The reversal of 21520814408 is 80441802512.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103298 + ... + 231758.

It is an arithmetic number, because the mean of its divisors is an integer number (1292970030).

Almost surely, 2^21520814408 is an apocalyptic number.

It is an amenable number.

21520814408 is a deficient number, since it is larger than the sum of its proper divisors (19854226552).

21520814408 is a wasteful number, since it uses less digits than its factorization.

21520814408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128997 (or 128993 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 35.

The spelling of 21520814408 in words is "twenty-one billion, five hundred twenty million, eight hundred fourteen thousand, four hundred eight".