21507604020761 has 4 divisors (see below), whose sum is σ = 21546923224272. Its totient is φ = 21468284817252.

The previous prime is 21507604020737. The next prime is 21507604020779. The reversal of 21507604020761 is 16702040670512.

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 21507604020761 - 2¹⁸ = 21507603758617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21507604820761) 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, 19659600935 + ... + 19659602028.

It is an arithmetic number, because the mean of its divisors is an integer number (5386730806068).

Almost surely, 2^{21507604020761} is an apocalyptic number.

It is an amenable number.

21507604020761 is a deficient number, since it is larger than the sum of its proper divisors (39319203511).

21507604020761 is an equidigital number, since it uses as much as digits as its factorization.

21507604020761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39319203510.

The product of its (nonzero) digits is 141120, while the sum is 41.

The spelling of 21507604020761 in words is "twenty-one trillion, five hundred seven billion, six hundred four million, twenty thousand, seven hundred sixty-one".