21500435043561 has 16 divisors (see below), whose sum is σ = 29720260503360. Its totient is φ = 13815540583680.

The previous prime is 21500435043517. The next prime is 21500435043589. The reversal of 21500435043561 is 16534053400512.

It is a happy number.

It is not a de Polignac number, because 21500435043561 - 2¹¹ = 21500435041513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21500435043761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1053003556 + ... + 1053023973.

It is an arithmetic number, because the mean of its divisors is an integer number (1857516281460).

Almost surely, 2^{21500435043561} is an apocalyptic number.

It is an amenable number.

21500435043561 is a deficient number, since it is larger than the sum of its proper divisors (8219825459799).

21500435043561 is a wasteful number, since it uses less digits than its factorization.

21500435043561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2106027656.

The product of its (nonzero) digits is 216000, while the sum is 39.

The spelling of 21500435043561 in words is "twenty-one trillion, five hundred billion, four hundred thirty-five million, forty-three thousand, five hundred sixty-one".