21516011653 has 4 divisors (see below), whose sum is σ = 21517488748. Its totient is φ = 21514534560.

The previous prime is 21516011639. The next prime is 21516011677. The reversal of 21516011653 is 35611061512.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12068560449 + 9447451204 = 109857^2 + 97198^2 .

It is a cyclic number.

It is not a de Polignac number, because 21516011653 - 2¹³ = 21516003461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516011603) 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, 716478 + ... + 745903.

It is an arithmetic number, because the mean of its divisors is an integer number (5379372187).

Almost surely, 2^21516011653 is an apocalyptic number.

It is an amenable number.

21516011653 is a deficient number, since it is larger than the sum of its proper divisors (1477095).

21516011653 is a wasteful number, since it uses less digits than its factorization.

21516011653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1477094.

The product of its (nonzero) digits is 5400, while the sum is 31.

The spelling of 21516011653 in words is "twenty-one billion, five hundred sixteen million, eleven thousand, six hundred fifty-three".