2661642021 has 4 divisors (see below), whose sum is σ = 3548856032. Its totient is φ = 1774428012.

The previous prime is 2661642019. The next prime is 2661642083. The reversal of 2661642021 is 1202461662.

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 not a de Polignac number, because 2661642021 - 2¹ = 2661642019 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2661642021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2661642521) 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, 443607001 + ... + 443607006.

It is an arithmetic number, because the mean of its divisors is an integer number (887214008).

Almost surely, 2^2661642021 is an apocalyptic number.

It is an amenable number.

2661642021 is a deficient number, since it is larger than the sum of its proper divisors (887214011).

2661642021 is an equidigital number, since it uses as much as digits as its factorization.

2661642021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 887214010.

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 2661642021 is about 51591.1040878173. The cubic root of 2661642021 is about 1385.8510274055.

The spelling of 2661642021 in words is "two billion, six hundred sixty-one million, six hundred forty-two thousand, twenty-one".