15540540021 has 24 divisors (see below), whose sum is σ = 25018830720. Its totient is φ = 9237718656.

The previous prime is 15540540007. The next prime is 15540540023. The reversal of 15540540021 is 12004504551.

It is not a de Polignac number, because 15540540021 - 2⁷ = 15540539893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15540540023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2670045 + ... + 2675858.

It is an arithmetic number, because the mean of its divisors is an integer number (1042451280).

Almost surely, 2^15540540021 is an apocalyptic number.

It is an amenable number.

15540540021 is a deficient number, since it is larger than the sum of its proper divisors (9478290699).

15540540021 is a wasteful number, since it uses less digits than its factorization.

15540540021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5345945 (or 5345942 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 27.

The spelling of 15540540021 in words is "fifteen billion, five hundred forty million, five hundred forty thousand, twenty-one".