21534042415 has 4 divisors (see below), whose sum is σ = 25840850904. Its totient is φ = 17227233928.

The previous prime is 21534042349. The next prime is 21534042449. The reversal of 21534042415 is 51424043512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21534042415 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2153404237 + ... + 2153404246.

It is an arithmetic number, because the mean of its divisors is an integer number (6460212726).

Almost surely, 2^21534042415 is an apocalyptic number.

21534042415 is a deficient number, since it is larger than the sum of its proper divisors (4306808489).

21534042415 is an equidigital number, since it uses as much as digits as its factorization.

21534042415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4306808488.

The product of its (nonzero) digits is 19200, while the sum is 31.

Adding to 21534042415 its reverse (51424043512), we get a palindrome (72958085927).

The spelling of 21534042415 in words is "twenty-one billion, five hundred thirty-four million, forty-two thousand, four hundred fifteen".