70806781 has 4 divisors (see below), whose sum is σ = 72142812. Its totient is φ = 69470752.

The previous prime is 70806779. The next prime is 70806797. The reversal of 70806781 is 18760807.

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: 18760807 = 13 ⋅1443139.

It can be written as a sum of positive squares in 2 ways, for example, as 23609881 + 47196900 = 4859^2 + 6870^2 .

It is a cyclic number.

It is not a de Polignac number, because 70806781 - 2¹ = 70806779 is a prime.

It is a super-2 number, since 2×70806781² = 10027200471163922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 70806781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (70806721) 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, 667936 + ... + 668041.

It is an arithmetic number, because the mean of its divisors is an integer number (18035703).

Almost surely, 2^70806781 is an apocalyptic number.

It is an amenable number.

70806781 is a deficient number, since it is larger than the sum of its proper divisors (1336031).

70806781 is a wasteful number, since it uses less digits than its factorization.

70806781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1336030.

The product of its (nonzero) digits is 18816, while the sum is 37.

The square root of 70806781 is about 8414.6765237887. The cubic root of 70806781 is about 413.7058070803.

It can be divided in two parts, 7080 and 6781, that added together give a triangular number (13861 = T₁₆₆).

The spelling of 70806781 in words is "seventy million, eight hundred six thousand, seven hundred eighty-one".