21521345470 has 16 divisors (see below), whose sum is σ = 38763884880. Its totient is φ = 8602879744.

The previous prime is 21521345407. The next prime is 21521345471. The reversal of 21521345470 is 7454312512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521345471) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 691315 + ... + 721774.

It is an arithmetic number, because the mean of its divisors is an integer number (2422742805).

Almost surely, 2^21521345470 is an apocalyptic number.

21521345470 is a deficient number, since it is larger than the sum of its proper divisors (17242539410).

21521345470 is a wasteful number, since it uses less digits than its factorization.

21521345470 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1414619.

The product of its (nonzero) digits is 33600, while the sum is 34.

Adding to 21521345470 its reverse (7454312512), we get a palindrome (28975657982).

The spelling of 21521345470 in words is "twenty-one billion, five hundred twenty-one million, three hundred forty-five thousand, four hundred seventy".