921631 has 4 divisors (see below), whose sum is σ = 923832. Its totient is φ = 919432.

The previous prime is 921629. The next prime is 921637. The reversal of 921631 is 136129.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 136129 = 7 ⋅19447.

It is a cyclic number.

It is not a de Polignac number, because 921631 - 2¹ = 921629 is a prime.

It is a super-2 number, since 2×921631² = 1698807400322, which contains 22 as substring.

It is a Duffinian number.

921631 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921637) 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, 256 + ... + 1381.

It is an arithmetic number, because the mean of its divisors is an integer number (230958).

2⁹²¹⁶³¹ is an apocalyptic number.

921631 is a deficient number, since it is larger than the sum of its proper divisors (2201).

921631 is a wasteful number, since it uses less digits than its factorization.

921631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2200.

The product of its digits is 324, while the sum is 22.

The square root of 921631 is about 960.0161456976. The cubic root of 921631 is about 97.3163230527.

The spelling of 921631 in words is "nine hundred twenty-one thousand, six hundred thirty-one".