720078921 has 6 divisors (see below), whose sum is σ = 1040114010. Its totient is φ = 480052608.

The previous prime is 720078899. The next prime is 720078937. The reversal of 720078921 is 129870027.

It can be written as a sum of positive squares in only one way, i.e., 574273296 + 145805625 = 23964^2 + 12075^2 .

It is not a de Polignac number, because 720078921 - 2⁵ = 720078889 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (720078971) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 40004376 + ... + 40004393.

It is an arithmetic number, because the mean of its divisors is an integer number (173352335).

Almost surely, 2^720078921 is an apocalyptic number.

It is an amenable number.

720078921 is a deficient number, since it is larger than the sum of its proper divisors (320035089).

720078921 is a wasteful number, since it uses less digits than its factorization.

720078921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80008775 (or 80008772 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 720078921 is about 26834.2862957076. The cubic root of 720078921 is about 896.3136959802.

The spelling of 720078921 in words is "seven hundred twenty million, seventy-eight thousand, nine hundred twenty-one".