21040051521 has 8 divisors (see below), whose sum is σ = 28069090240. Its totient is φ = 14018856912.

The previous prime is 21040051511. The next prime is 21040051559. The reversal of 21040051521 is 12515004012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21040051521 - 2¹³ = 21040043329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040051511) 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, 1954765 + ... + 1965498.

It is an arithmetic number, because the mean of its divisors is an integer number (3508636280).

Almost surely, 2^21040051521 is an apocalyptic number.

It is an amenable number.

21040051521 is a deficient number, since it is larger than the sum of its proper divisors (7029038719).

21040051521 is a wasteful number, since it uses less digits than its factorization.

21040051521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3922055.

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 21040051521 its reverse (12515004012), we get a palindrome (33555055533).

The spelling of 21040051521 in words is "twenty-one billion, forty million, fifty-one thousand, five hundred twenty-one".