921978973 has 4 divisors (see below), whose sum is σ = 925652448. Its totient is φ = 918305500.

The previous prime is 921978929. The next prime is 921978997. The reversal of 921978973 is 379879129.

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: 379879129 = 7 ⋅54268447.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-921978973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921978373) 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, 1836361 + ... + 1836862.

It is an arithmetic number, because the mean of its divisors is an integer number (231413112).

Almost surely, 2^921978973 is an apocalyptic number.

It is an amenable number.

921978973 is a deficient number, since it is larger than the sum of its proper divisors (3673475).

921978973 is a wasteful number, since it uses less digits than its factorization.

921978973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3673474.

The product of its digits is 1714608, while the sum is 55.

The square root of 921978973 is about 30364.1066557210. The cubic root of 921978973 is about 973.2856916565.

The spelling of 921978973 in words is "nine hundred twenty-one million, nine hundred seventy-eight thousand, nine hundred seventy-three".