1661012231 has 4 divisors (see below), whose sum is σ = 1672012464. Its totient is φ = 1650012000.

The previous prime is 1661012179. The next prime is 1661012239. The reversal of 1661012231 is 1322101661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1322101661 = 223 ⋅5928707.

It is a cyclic number.

It is not a de Polignac number, because 1661012231 - 2¹⁰ = 1661011207 is a prime.

It is a super-2 number, since 2×1661012231² = 5517923263063194722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1661012197 and 1661012206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661012239) 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, 5499890 + ... + 5500191.

It is an arithmetic number, because the mean of its divisors is an integer number (418003116).

Almost surely, 2^1661012231 is an apocalyptic number.

1661012231 is a deficient number, since it is larger than the sum of its proper divisors (11000233).

1661012231 is a wasteful number, since it uses less digits than its factorization.

1661012231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11000232.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1661012231 is about 40755.5177982074. The cubic root of 1661012231 is about 1184.2887673643.

Adding to 1661012231 its reverse (1322101661), we get a palindrome (2983113892).

The spelling of 1661012231 in words is "one billion, six hundred sixty-one million, twelve thousand, two hundred thirty-one".