21155144022565 has 16 divisors (see below), whose sum is σ = 29012883454080. Its totient is φ = 14506327218240.

The previous prime is 21155144022511. The next prime is 21155144022577. The reversal of 21155144022565 is 56522044155112.

It is not a de Polignac number, because 21155144022565 - 2⁷ = 21155144022437 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9037555 + ... + 11134975.

It is an arithmetic number, because the mean of its divisors is an integer number (1813305215880).

Almost surely, 2^{21155144022565} is an apocalyptic number.

It is an amenable number.

21155144022565 is a deficient number, since it is larger than the sum of its proper divisors (7857739431515).

21155144022565 is a wasteful number, since it uses less digits than its factorization.

21155144022565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2385612.

The product of its (nonzero) digits is 480000, while the sum is 43.

Adding to 21155144022565 its reverse (56522044155112), we get a palindrome (77677188177677).

The spelling of 21155144022565 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred forty-four million, twenty-two thousand, five hundred sixty-five".