71977021 has 4 divisors (see below), whose sum is σ = 73335132. Its totient is φ = 70618912.

The previous prime is 71976977. The next prime is 71977039. The reversal of 71977021 is 12077917.

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

It can be written as a sum of positive squares in 2 ways, for example, as 42968025 + 29008996 = 6555^2 + 5386^2 .

It is a cyclic number.

It is not a de Polignac number, because 71977021 - 2¹³ = 71968829 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 (71977091) 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, 678976 + ... + 679081.

It is an arithmetic number, because the mean of its divisors is an integer number (18333783).

Almost surely, 2^71977021 is an apocalyptic number.

It is an amenable number.

71977021 is a deficient number, since it is larger than the sum of its proper divisors (1358111).

71977021 is a wasteful number, since it uses less digits than its factorization.

71977021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1358110.

The product of its (nonzero) digits is 6174, while the sum is 34.

The square root of 71977021 is about 8483.9272156237. The cubic root of 71977021 is about 415.9725022659.

The spelling of 71977021 in words is "seventy-one million, nine hundred seventy-seven thousand, twenty-one".