21141904961 has 4 divisors (see below), whose sum is σ = 21145305300. Its totient is φ = 21138504624.

The previous prime is 21141904937. The next prime is 21141904967. The reversal of 21141904961 is 16940914112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7881000625 + 13260904336 = 88775^2 + 115156^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21141904961 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21141904967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1690826 + ... + 1703283.

It is an arithmetic number, because the mean of its divisors is an integer number (5286326325).

Almost surely, 2^21141904961 is an apocalyptic number.

It is an amenable number.

21141904961 is a deficient number, since it is larger than the sum of its proper divisors (3400339).

21141904961 is an equidigital number, since it uses as much as digits as its factorization.

21141904961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3400338.

The product of its (nonzero) digits is 15552, while the sum is 38.

The spelling of 21141904961 in words is "twenty-one billion, one hundred forty-one million, nine hundred four thousand, nine hundred sixty-one".