21661353004651 has 8 divisors (see below), whose sum is σ = 22165179309680. Its totient is φ = 21157530059232.

The previous prime is 21661353004619. The next prime is 21661353004667. The reversal of 21661353004651 is 15640035316612.

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

It is a cyclic number.

It is not a de Polignac number, because 21661353004651 - 2⁵ = 21661353004619 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21661353004598 and 21661353004607.

It is not an unprimeable number, because it can be changed into a prime (21661353004691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16161181 + ... + 17450113.

It is an arithmetic number, because the mean of its divisors is an integer number (2770647413710).

Almost surely, 2^{21661353004651} is an apocalyptic number.

21661353004651 is a deficient number, since it is larger than the sum of its proper divisors (503826305029).

21661353004651 is a wasteful number, since it uses less digits than its factorization.

21661353004651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1679805.

The product of its (nonzero) digits is 388800, while the sum is 43.

The spelling of 21661353004651 in words is "twenty-one trillion, six hundred sixty-one billion, three hundred fifty-three million, four thousand, six hundred fifty-one".