78001781 has 12 divisors (see below), whose sum is σ = 92144160. Its totient is φ = 65454480.

The previous prime is 78001747. The next prime is 78001787. The reversal of 78001781 is 18710087.

It is not a de Polignac number, because 78001781 - 2¹⁸ = 77739637 is a prime.

It is a super-2 number, since 2×78001781² = 12168555678343922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78001787) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19121 + ... + 22838.

It is an arithmetic number, because the mean of its divisors is an integer number (7678680).

Almost surely, 2^78001781 is an apocalyptic number.

It is an amenable number.

78001781 is a deficient number, since it is larger than the sum of its proper divisors (14142379).

78001781 is a wasteful number, since it uses less digits than its factorization.

78001781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41996 (or 41983 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 32.

The square root of 78001781 is about 8831.8616950222. The cubic root of 78001781 is about 427.2691201130.

The spelling of 78001781 in words is "seventy-eight million, one thousand, seven hundred eighty-one".