21151224354665 has 8 divisors (see below), whose sum is σ = 25860364871688. Its totient is φ = 16601715719680.

The previous prime is 21151224354649. The next prime is 21151224354671. The reversal of 21151224354665 is 56645342215112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2449863561616 + 18701360793049 = 1565204^2 + 4324507^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21151224354665 - 2⁴ = 21151224354649 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39907970216 + ... + 39907970745.

It is an arithmetic number, because the mean of its divisors is an integer number (3232545608961).

Almost surely, 2^{21151224354665} is an apocalyptic number.

It is an amenable number.

21151224354665 is a deficient number, since it is larger than the sum of its proper divisors (4709140517023).

21151224354665 is an equidigital number, since it uses as much as digits as its factorization.

21151224354665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79815941019.

The product of its digits is 1728000, while the sum is 47.

Adding to 21151224354665 its reverse (56645342215112), we get a palindrome (77796566569777).

The spelling of 21151224354665 in words is "twenty-one trillion, one hundred fifty-one billion, two hundred twenty-four million, three hundred fifty-four thousand, six hundred sixty-five".