81401861 has 4 divisors (see below), whose sum is σ = 81856800. Its totient is φ = 80946924.

The previous prime is 81401839. The next prime is 81401891. The reversal of 81401861 is 16810418.

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: 16810418 = 2 ⋅8405209.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81401861 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 (81401891) 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, 227201 + ... + 227558.

It is an arithmetic number, because the mean of its divisors is an integer number (20464200).

Almost surely, 2^81401861 is an apocalyptic number.

It is an amenable number.

81401861 is a deficient number, since it is larger than the sum of its proper divisors (454939).

81401861 is a wasteful number, since it uses less digits than its factorization.

81401861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454938.

The product of its (nonzero) digits is 1536, while the sum is 29.

The square root of 81401861 is about 9022.2979888718. The cubic root of 81401861 is about 433.3892266496.

It can be divided in two parts, 8140 and 1861, that added together give a palindrome (10001).

The spelling of 81401861 in words is "eighty-one million, four hundred one thousand, eight hundred sixty-one".