21208041461657 has 4 divisors (see below), whose sum is σ = 21211054402560. Its totient is φ = 21205028520756.

The previous prime is 21208041461617. The next prime is 21208041461741. The reversal of 21208041461657 is 75616414080212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21208041461657 - 2¹⁰ = 21208041460633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21208041461617) 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 3 ways as a sum of consecutive naturals, for example, 1506459893 + ... + 1506473970.

It is an arithmetic number, because the mean of its divisors is an integer number (5302763600640).

Almost surely, 2^{21208041461657} is an apocalyptic number.

It is an amenable number.

21208041461657 is a deficient number, since it is larger than the sum of its proper divisors (3012940903).

21208041461657 is an equidigital number, since it uses as much as digits as its factorization.

21208041461657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3012940902.

The product of its (nonzero) digits is 645120, while the sum is 47.

The spelling of 21208041461657 in words is "twenty-one trillion, two hundred eight billion, forty-one million, four hundred sixty-one thousand, six hundred fifty-seven".