21611666047461 has 16 divisors (see below), whose sum is σ = 32932127743488. Its totient is φ = 12349499007600.

The previous prime is 21611666047393. The next prime is 21611666047463. The reversal of 21611666047461 is 16474066611612.

It is not a de Polignac number, because 21611666047461 - 2²⁷ = 21611531829733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611666047463) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18893146 + ... + 20004356.

It is an arithmetic number, because the mean of its divisors is an integer number (2058257983968).

Almost surely, 2^{21611666047461} is an apocalyptic number.

21611666047461 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21611666047461 is a deficient number, since it is larger than the sum of its proper divisors (11320461696027).

21611666047461 is a wasteful number, since it uses less digits than its factorization.

21611666047461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2037352.

The product of its (nonzero) digits is 1741824, while the sum is 51.

The spelling of 21611666047461 in words is "twenty-one trillion, six hundred eleven billion, six hundred sixty-six million, forty-seven thousand, four hundred sixty-one".