207921 has 8 divisors (see below), whose sum is σ = 316864. Its totient is φ = 118800.

The previous prime is 207877. The next prime is 207923. The reversal of 207921 is 129702.

It is a happy number.

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

It is not a de Polignac number, because 207921 - 2⁹ = 207409 is a prime.

It is a super-2 number, since 2×207921² = 86462284482, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 9901 = 207921 / (2 + 0 + 7 + 9 + 2 + 1).

It is a Duffinian number.

207921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (207923) 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, 4930 + ... + 4971.

It is an arithmetic number, because the mean of its divisors is an integer number (39608).

2²⁰⁷⁹²¹ is an apocalyptic number.

207921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

207921 is a deficient number, since it is larger than the sum of its proper divisors (108943).

207921 is an equidigital number, since it uses as much as digits as its factorization.

207921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9911.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 207921 is about 455.9835523349. The cubic root of 207921 is about 59.2424192263.

It can be divided in two parts, 207 and 921, that added together give a triangular number (1128 = T₄₇).

The spelling of 207921 in words is "two hundred seven thousand, nine hundred twenty-one".