1642573661 has 4 divisors (see below), whose sum is σ = 1650828000. Its totient is φ = 1634319324.

The previous prime is 1642573649. The next prime is 1642573679. The reversal of 1642573661 is 1663752461.

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 a de Polignac number, because none of the positive numbers 2^k-1642573661 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 (1642573561) 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, 4126871 + ... + 4127268.

It is an arithmetic number, because the mean of its divisors is an integer number (412707000).

Almost surely, 2^1642573661 is an apocalyptic number.

It is an amenable number.

1642573661 is a deficient number, since it is larger than the sum of its proper divisors (8254339).

1642573661 is an equidigital number, since it uses as much as digits as its factorization.

1642573661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8254338.

The product of its digits is 181440, while the sum is 41.

The square root of 1642573661 is about 40528.6770201052. The cubic root of 1642573661 is about 1179.8902658178.

The spelling of 1642573661 in words is "one billion, six hundred forty-two million, five hundred seventy-three thousand, six hundred sixty-one".