921978607 has 4 divisors (see below), whose sum is σ = 1005794856. Its totient is φ = 838162360.

The previous prime is 921978593. The next prime is 921978611. The reversal of 921978607 is 706879129.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 921978607 - 2¹⁵ = 921945839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921978107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41908108 + ... + 41908129.

It is an arithmetic number, because the mean of its divisors is an integer number (251448714).

Almost surely, 2^921978607 is an apocalyptic number.

921978607 is a deficient number, since it is larger than the sum of its proper divisors (83816249).

921978607 is a wasteful number, since it uses less digits than its factorization.

921978607 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83816248.

The product of its (nonzero) digits is 381024, while the sum is 49.

The square root of 921978607 is about 30364.1006288676. The cubic root of 921978607 is about 973.2855628673.

The spelling of 921978607 in words is "nine hundred twenty-one million, nine hundred seventy-eight thousand, six hundred seven".