921672721 has 8 divisors (see below), whose sum is σ = 968667840. Its totient is φ = 875254512.

The previous prime is 921672683. The next prime is 921672733. The reversal of 921672721 is 127276129.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 921672721 - 2⁷ = 921672593 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (921673721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140950 + ... + 147343.

It is an arithmetic number, because the mean of its divisors is an integer number (121083480).

Almost surely, 2^921672721 is an apocalyptic number.

It is an amenable number.

921672721 is a deficient number, since it is larger than the sum of its proper divisors (46995119).

921672721 is a wasteful number, since it uses less digits than its factorization.

921672721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288455.

The product of its digits is 21168, while the sum is 37.

The square root of 921672721 is about 30359.0632431240. The cubic root of 921672721 is about 973.1779149039.

The spelling of 921672721 in words is "nine hundred twenty-one million, six hundred seventy-two thousand, seven hundred twenty-one".