21520195074 has 128 divisors (see below), whose sum is σ = 57605376000. Its totient is φ = 5817489984.

The previous prime is 21520195061. The next prime is 21520195141. The reversal of 21520195074 is 47059102512.

21520195074 is a `hidden beast` number, since 2 + 1 + 520 + 19 + 50 + 74 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7676157 + ... + 7678959.

It is an arithmetic number, because the mean of its divisors is an integer number (450042000).

Almost surely, 2^21520195074 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21520195074, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28802688000).

21520195074 is an abundant number, since it is smaller than the sum of its proper divisors (36085180926).

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

21520195074 is a wasteful number, since it uses less digits than its factorization.

21520195074 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3909 (or 3903 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

Adding to 21520195074 its reverse (47059102512), we get a palindrome (68579297586).

The spelling of 21520195074 in words is "twenty-one billion, five hundred twenty million, one hundred ninety-five thousand, seventy-four".