71812978 has 4 divisors (see below), whose sum is σ = 107719470. Its totient is φ = 35906488.

The previous prime is 71812973. The next prime is 71812991. The reversal of 71812978 is 87921817.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87921817 = 83 ⋅1059299.

It can be written as a sum of positive squares in only one way, i.e., 57501889 + 14311089 = 7583^2 + 3783^2 .

It is not an unprimeable number, because it can be changed into a prime (71812973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 17953243 + ... + 17953246.

Almost surely, 2^71812978 is an apocalyptic number.

71812978 is a deficient number, since it is larger than the sum of its proper divisors (35906492).

71812978 is a wasteful number, since it uses less digits than its factorization.

71812978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35906491.

The product of its digits is 56448, while the sum is 43.

The square root of 71812978 is about 8474.2538314591. The cubic root of 71812978 is about 415.6562472446.

The spelling of 71812978 in words is "seventy-one million, eight hundred twelve thousand, nine hundred seventy-eight".