81421762 has 4 divisors (see below), whose sum is σ = 122132646. Its totient is φ = 40710880.

The previous prime is 81421729. The next prime is 81421787. The reversal of 81421762 is 26712418.

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., 52142841 + 29278921 = 7221^2 + 5411^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20355439 + ... + 20355442.

Almost surely, 2^81421762 is an apocalyptic number.

81421762 is a deficient number, since it is larger than the sum of its proper divisors (40710884).

81421762 is a wasteful number, since it uses less digits than its factorization.

81421762 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40710883.

The product of its digits is 5376, while the sum is 31.

The square root of 81421762 is about 9023.4008001418. The cubic root of 81421762 is about 433.4245418792.

The spelling of 81421762 in words is "eighty-one million, four hundred twenty-one thousand, seven hundred sixty-two".