21522501947 has 4 divisors (see below), whose sum is σ = 21712966680. Its totient is φ = 21332037216.

The previous prime is 21522501941. The next prime is 21522501977. The reversal of 21522501947 is 74910522512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21522501947 - 2¹² = 21522497851 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21522501947.

It is not an unprimeable number, because it can be changed into a prime (21522501941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 95232197 + ... + 95232422.

It is an arithmetic number, because the mean of its divisors is an integer number (5428241670).

Almost surely, 2^21522501947 is an apocalyptic number.

21522501947 is a deficient number, since it is larger than the sum of its proper divisors (190464733).

21522501947 is a wasteful number, since it uses less digits than its factorization.

21522501947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190464732.

The product of its (nonzero) digits is 50400, while the sum is 38.

The spelling of 21522501947 in words is "twenty-one billion, five hundred twenty-two million, five hundred one thousand, nine hundred forty-seven".