1665326631621 has 32 divisors (see below), whose sum is σ = 2251900846080. Its totient is φ = 1094606521344.

The previous prime is 1665326631611. The next prime is 1665326631637. The reversal of 1665326631621 is 1261366235661.

It is not a de Polignac number, because 1665326631621 - 2⁶ = 1665326631557 is a prime.

It is a super-2 number, since 2×1665326631621² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665326631611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 72271420 + ... + 72294458.

It is an arithmetic number, because the mean of its divisors is an integer number (70371901440).

Almost surely, 2^{1665326631621} is an apocalyptic number.

It is an amenable number.

1665326631621 is a deficient number, since it is larger than the sum of its proper divisors (586574214459).

1665326631621 is a wasteful number, since it uses less digits than its factorization.

1665326631621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24345.

The product of its digits is 1399680, while the sum is 48.

The spelling of 1665326631621 in words is "one trillion, six hundred sixty-five billion, three hundred twenty-six million, six hundred thirty-one thousand, six hundred twenty-one".