21816154651 has 4 divisors (see below), whose sum is σ = 21887217352. Its totient is φ = 21745091952.

The previous prime is 21816154589. The next prime is 21816154687. The reversal of 21816154651 is 15645161812.

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

It is a cyclic number.

It is not a de Polignac number, because 21816154651 - 2¹⁵ = 21816121883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21816152651) 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, 35530890 + ... + 35531503.

It is an arithmetic number, because the mean of its divisors is an integer number (5471804338).

Almost surely, 2^21816154651 is an apocalyptic number.

21816154651 is a deficient number, since it is larger than the sum of its proper divisors (71062701).

21816154651 is an equidigital number, since it uses as much as digits as its factorization.

21816154651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71062700.

The product of its digits is 57600, while the sum is 40.

The spelling of 21816154651 in words is "twenty-one billion, eight hundred sixteen million, one hundred fifty-four thousand, six hundred fifty-one".