15545345021 has 4 divisors (see below), whose sum is σ = 15595981632. Its totient is φ = 15494708412.

The previous prime is 15545345009. The next prime is 15545345029. The reversal of 15545345021 is 12054354551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12054354551 = 8941 ⋅1348211.

It is a cyclic number.

It is not a de Polignac number, because 15545345021 - 2²⁶ = 15478236157 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 (15545345029) 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, 25317845 + ... + 25318458.

It is an arithmetic number, because the mean of its divisors is an integer number (3898995408).

Almost surely, 2^15545345021 is an apocalyptic number.

It is an amenable number.

15545345021 is a deficient number, since it is larger than the sum of its proper divisors (50636611).

15545345021 is an equidigital number, since it uses as much as digits as its factorization.

15545345021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50636610.

The product of its (nonzero) digits is 60000, while the sum is 35.

Adding to 15545345021 its reverse (12054354551), we get a palindrome (27599699572).

The spelling of 15545345021 in words is "fifteen billion, five hundred forty-five million, three hundred forty-five thousand, twenty-one".