1623201661 has 4 divisors (see below), whose sum is σ = 1623311392. Its totient is φ = 1623091932.

The previous prime is 1623201653. The next prime is 1623201677. The reversal of 1623201661 is 1661023261.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1623201661 - 2³ = 1623201653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1623201611) 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, 28431 + ... + 63676.

It is an arithmetic number, because the mean of its divisors is an integer number (405827848).

Almost surely, 2^1623201661 is an apocalyptic number.

It is an amenable number.

1623201661 is a deficient number, since it is larger than the sum of its proper divisors (109731).

1623201661 is an equidigital number, since it uses as much as digits as its factorization.

1623201661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109730.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 1623201661 is about 40288.9769167697. The cubic root of 1623201661 is about 1175.2334917905.

The spelling of 1623201661 in words is "one billion, six hundred twenty-three million, two hundred one thousand, six hundred sixty-one".