18961861 has 4 divisors (see below), whose sum is σ = 18994752. Its totient is φ = 18928972.

The previous prime is 18961847. The next prime is 18961879. The reversal of 18961861 is 16816981.

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: 16816981 = 37 ⋅454513.

It is a cyclic number.

It is not a de Polignac number, because 18961861 - 2¹¹ = 18959813 is a prime.

It is a super-3 number, since 3×18961861³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18961561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15565 + ... + 16738.

It is an arithmetic number, because the mean of its divisors is an integer number (4748688).

Almost surely, 2^18961861 is an apocalyptic number.

It is an amenable number.

18961861 is a deficient number, since it is larger than the sum of its proper divisors (32891).

18961861 is an equidigital number, since it uses as much as digits as its factorization.

18961861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32890.

The product of its digits is 20736, while the sum is 40.

The square root of 18961861 is about 4354.5219025744. The cubic root of 18961861 is about 266.6615011152.

The spelling of 18961861 in words is "eighteen million, nine hundred sixty-one thousand, eight hundred sixty-one".