69721 has 4 divisors (see below), whose sum is σ = 70452. Its totient is φ = 68992.

The previous prime is 69709. The next prime is 69737. The reversal of 69721 is 12796.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1600 + 68121 = 40^2 + 261^2 .

It is a cyclic number.

It is not a de Polignac number, because 69721 - 2⁷ = 69593 is a prime.

It is a super-2 number, since 2×69721² = 9722035682, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (69761) 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, 196 + ... + 421.

It is an arithmetic number, because the mean of its divisors is an integer number (17613).

2⁶⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

69721 is a deficient number, since it is larger than the sum of its proper divisors (731).

69721 is a wasteful number, since it uses less digits than its factorization.

69721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 730.

The product of its digits is 756, while the sum is 25.

The square root of 69721 is about 264.0473442396. The cubic root of 69721 is about 41.1580258727.

Subtracting from 69721 its sum of digits (25), we obtain a palindrome (69696).

The spelling of 69721 in words is "sixty-nine thousand, seven hundred twenty-one".