921661 has 8 divisors (see below), whose sum is σ = 1025024. Its totient is φ = 822960.

The previous prime is 921647. The next prime is 921667. The reversal of 921661 is 166129.

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

It is a cyclic number.

It is not a de Polignac number, because 921661 - 2⁵ = 921629 is a prime.

921661 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 741 + ... + 1546.

It is an arithmetic number, because the mean of its divisors is an integer number (128128).

2⁹²¹⁶⁶¹ is an apocalyptic number.

It is an amenable number.

921661 is a deficient number, since it is larger than the sum of its proper divisors (103363).

921661 is a wasteful number, since it uses less digits than its factorization.

921661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2331.

The product of its digits is 648, while the sum is 25.

The square root of 921661 is about 960.0317703076. The cubic root of 921661 is about 97.3173789554.

The spelling of 921661 in words is "nine hundred twenty-one thousand, six hundred sixty-one".