20661533601 has 4 divisors (see below), whose sum is σ = 27548711472. Its totient is φ = 13774355732.

The previous prime is 20661533587. The next prime is 20661533609. The reversal of 20661533601 is 10633516602.

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 20661533601 - 2⁵ = 20661533569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20661533609) 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, 3443588931 + ... + 3443588936.

It is an arithmetic number, because the mean of its divisors is an integer number (6887177868).

Almost surely, 2^20661533601 is an apocalyptic number.

It is an amenable number.

20661533601 is a deficient number, since it is larger than the sum of its proper divisors (6887177871).

20661533601 is an equidigital number, since it uses as much as digits as its factorization.

20661533601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6887177870.

The product of its (nonzero) digits is 19440, while the sum is 33.

The spelling of 20661533601 in words is "twenty billion, six hundred sixty-one million, five hundred thirty-three thousand, six hundred one".