78216649 has 4 divisors (see below), whose sum is σ = 89390464. Its totient is φ = 67042836.

The previous prime is 78216647. The next prime is 78216667. The reversal of 78216649 is 94661287.

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.

It is not a de Polignac number, because 78216649 - 2¹ = 78216647 is a prime.

It is a super-2 number, since 2×78216649² = 12235688361578402, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78216647) 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, 5586897 + ... + 5586910.

It is an arithmetic number, because the mean of its divisors is an integer number (22347616).

Almost surely, 2^78216649 is an apocalyptic number.

It is an amenable number.

78216649 is a deficient number, since it is larger than the sum of its proper divisors (11173815).

78216649 is a wasteful number, since it uses less digits than its factorization.

78216649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11173814.

The product of its digits is 145152, while the sum is 43.

The square root of 78216649 is about 8844.0176955951. The cubic root of 78216649 is about 427.6610867687.

The spelling of 78216649 in words is "seventy-eight million, two hundred sixteen thousand, six hundred forty-nine".