20421646634261 has 4 divisors (see below), whose sum is σ = 20422339322112. Its totient is φ = 20420953946412.

The previous prime is 20421646634237. The next prime is 20421646634297. The reversal of 20421646634261 is 16243664612402.

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 20421646634261 - 2³⁰ = 20420572892437 is a prime.

It is a super-2 number, since 2×20421646634261² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421646630261) 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, 346299701 + ... + 346358666.

It is an arithmetic number, because the mean of its divisors is an integer number (5105584830528).

Almost surely, 2^{20421646634261} is an apocalyptic number.

It is an amenable number.

20421646634261 is a deficient number, since it is larger than the sum of its proper divisors (692687851).

20421646634261 is an equidigital number, since it uses as much as digits as its factorization.

20421646634261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 692687850.

The product of its (nonzero) digits is 1990656, while the sum is 47.

The spelling of 20421646634261 in words is "twenty trillion, four hundred twenty-one billion, six hundred forty-six million, six hundred thirty-four thousand, two hundred sixty-one".