16553530621 has 4 divisors (see below), whose sum is σ = 16564924732. Its totient is φ = 16542136512.

The previous prime is 16553530619. The next prime is 16553530633. The reversal of 16553530621 is 12603535561.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7954677721 + 8598852900 = 89189^2 + 92730^2 .

It is a cyclic number.

It is not a de Polignac number, because 16553530621 - 2¹ = 16553530619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16553530661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5694876 + ... + 5697781.

It is an arithmetic number, because the mean of its divisors is an integer number (4141231183).

Almost surely, 2^16553530621 is an apocalyptic number.

It is an amenable number.

16553530621 is a deficient number, since it is larger than the sum of its proper divisors (11394111).

16553530621 is a wasteful number, since it uses less digits than its factorization.

16553530621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11394110.

The product of its (nonzero) digits is 81000, while the sum is 37.

The spelling of 16553530621 in words is "sixteen billion, five hundred fifty-three million, five hundred thirty thousand, six hundred twenty-one".