21653950511 has 4 divisors (see below), whose sum is σ = 21656827272. Its totient is φ = 21651073752.

The previous prime is 21653950489. The next prime is 21653950517. The reversal of 21653950511 is 11505935612.

It is a happy number.

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-21653950511 is a prime.

It is a super-2 number, since 2×21653950511² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21653950517) 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, 1427060 + ... + 1442153.

It is an arithmetic number, because the mean of its divisors is an integer number (5414206818).

Almost surely, 2^21653950511 is an apocalyptic number.

21653950511 is a deficient number, since it is larger than the sum of its proper divisors (2876761).

21653950511 is an equidigital number, since it uses as much as digits as its factorization.

21653950511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2876760.

The product of its (nonzero) digits is 40500, while the sum is 38.

The spelling of 21653950511 in words is "twenty-one billion, six hundred fifty-three million, nine hundred fifty thousand, five hundred eleven".