72780817 has 4 divisors (see below), whose sum is σ = 73304560. Its totient is φ = 72257076.

The previous prime is 72780803. The next prime is 72780823. The reversal of 72780817 is 71808727.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71808727 = 29 ⋅2476163.

It is a cyclic number.

It is not a de Polignac number, because 72780817 - 2¹⁹ = 72256529 is a prime.

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 72780817.

It is not an unprimeable number, because it can be changed into a prime (72786817) 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, 261663 + ... + 261940.

It is an arithmetic number, because the mean of its divisors is an integer number (18326140).

Almost surely, 2^72780817 is an apocalyptic number.

It is an amenable number.

72780817 is a deficient number, since it is larger than the sum of its proper divisors (523743).

72780817 is a wasteful number, since it uses less digits than its factorization.

72780817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523742.

The product of its (nonzero) digits is 43904, while the sum is 40.

The square root of 72780817 is about 8531.1673878784. The cubic root of 72780817 is about 417.5152171537.

The spelling of 72780817 in words is "seventy-two million, seven hundred eighty thousand, eight hundred seventeen".