21047556461 has 6 divisors (see below), whose sum is σ = 21798361962. Its totient is φ = 20321777840.

The previous prime is 21047556437. The next prime is 21047556529. The reversal of 21047556461 is 16465574012.

It can be written as a sum of positive squares in 3 ways, for example, as 1330060900 + 19717495561 = 36470^2 + 140419^2 .

It is not a de Polignac number, because 21047556461 - 2¹⁰ = 21047555437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21047556661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12512570 + ... + 12514251.

It is an arithmetic number, because the mean of its divisors is an integer number (3633060327).

Almost surely, 2^21047556461 is an apocalyptic number.

It is an amenable number.

21047556461 is a deficient number, since it is larger than the sum of its proper divisors (750805501).

21047556461 is an equidigital number, since it uses as much as digits as its factorization.

21047556461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25026879 (or 25026850 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 41.

The spelling of 21047556461 in words is "twenty-one billion, forty-seven million, five hundred fifty-six thousand, four hundred sixty-one".