81893402 has 4 divisors (see below), whose sum is σ = 122840106. Its totient is φ = 40946700.

The previous prime is 81893393. The next prime is 81893429. The reversal of 81893402 is 20439818.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 74114881 + 7778521 = 8609^2 + 2789^2 .

It is a super-2 number, since 2×81893402² = 13413058582267208, which contains 22 as substring.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20473349 + ... + 20473352.

Almost surely, 2^81893402 is an apocalyptic number.

81893402 is a deficient number, since it is larger than the sum of its proper divisors (40946704).

81893402 is a wasteful number, since it uses less digits than its factorization.

81893402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40946703.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 81893402 is about 9049.4973341065. The cubic root of 81893402 is about 434.2598096090.

The spelling of 81893402 in words is "eighty-one million, eight hundred ninety-three thousand, four hundred two".