1954131661 has 4 divisors (see below), whose sum is σ = 1955660800. Its totient is φ = 1952602524.

The previous prime is 1954131649. The next prime is 1954131731. The reversal of 1954131661 is 1661314591.

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 an emirpimes, since its reverse is a distinct semiprime: 1661314591 = 2213 ⋅750707.

It is a cyclic number.

It is not a de Polignac number, because 1954131661 - 2⁷ = 1954131533 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 1954131661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1954131611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 762651 + ... + 765208.

It is an arithmetic number, because the mean of its divisors is an integer number (488915200).

Almost surely, 2^1954131661 is an apocalyptic number.

It is an amenable number.

1954131661 is a deficient number, since it is larger than the sum of its proper divisors (1529139).

1954131661 is a wasteful number, since it uses less digits than its factorization.

1954131661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1529138.

The product of its digits is 19440, while the sum is 37.

The square root of 1954131661 is about 44205.5614261373. The cubic root of 1954131661 is about 1250.2147174617.

The spelling of 1954131661 in words is "one billion, nine hundred fifty-four million, one hundred thirty-one thousand, six hundred sixty-one".