21661020450619 has 48 divisors (see below), whose sum is σ = 25363854673920. Its totient is φ = 18444337049600.

The previous prime is 21661020450577. The next prime is 21661020450679. The reversal of 21661020450619 is 91605402016612.

It is not a de Polignac number, because 21661020450619 - 2⁷ = 21661020450491 is a prime.

It is a super-2 number, since 2×21661020450619² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21661020450679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 41941974 + ... + 42455284.

It is an arithmetic number, because the mean of its divisors is an integer number (528413639040).

Almost surely, 2^{21661020450619} is an apocalyptic number.

21661020450619 is a deficient number, since it is larger than the sum of its proper divisors (3702834223301).

21661020450619 is a wasteful number, since it uses less digits than its factorization.

21661020450619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513672 (or 513661 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 43.

The spelling of 21661020450619 in words is "twenty-one trillion, six hundred sixty-one billion, twenty million, four hundred fifty thousand, six hundred nineteen".