1621415231661 has 8 divisors (see below), whose sum is σ = 2191501865920. Its totient is φ = 1066136042592.

The previous prime is 1621415231651. The next prime is 1621415231699. The reversal of 1621415231661 is 1661325141261.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1621415231661 - 2²⁵ = 1621381677229 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 (1621415231651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3701861041 + ... + 3701861478.

It is an arithmetic number, because the mean of its divisors is an integer number (273937733240).

Almost surely, 2^{1621415231661} is an apocalyptic number.

It is an amenable number.

1621415231661 is a deficient number, since it is larger than the sum of its proper divisors (570086634259).

1621415231661 is an equidigital number, since it uses as much as digits as its factorization.

1621415231661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7403722595.

The product of its digits is 51840, while the sum is 39.

The spelling of 1621415231661 in words is "one trillion, six hundred twenty-one billion, four hundred fifteen million, two hundred thirty-one thousand, six hundred sixty-one".