21165139537 has 16 divisors (see below), whose sum is σ = 21639242880. Its totient is φ = 20697840000.

The previous prime is 21165139529. The next prime is 21165139543. The reversal of 21165139537 is 73593156112.

It is a cyclic number.

It is not a de Polignac number, because 21165139537 - 2³ = 21165139529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21165139493 and 21165139502.

It is not an unprimeable number, because it can be changed into a prime (21165133537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2726053 + ... + 2733805.

It is an arithmetic number, because the mean of its divisors is an integer number (1352452680).

Almost surely, 2^21165139537 is an apocalyptic number.

It is an amenable number.

21165139537 is a deficient number, since it is larger than the sum of its proper divisors (474103343).

21165139537 is a wasteful number, since it uses less digits than its factorization.

21165139537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8184.

The product of its digits is 170100, while the sum is 43.

The spelling of 21165139537 in words is "twenty-one billion, one hundred sixty-five million, one hundred thirty-nine thousand, five hundred thirty-seven".