661969 has 8 divisors (see below), whose sum is σ = 825408. Its totient is φ = 515760.

The previous prime is 661961. The next prime is 661987. The reversal of 661969 is 969166.

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

It is not a de Polignac number, because 661969 - 2³ = 661961 is a prime.

It is a super-2 number, since 2×661969² = 876405913922, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (661961) 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, 4222 + ... + 4375.

It is an arithmetic number, because the mean of its divisors is an integer number (103176).

2⁶⁶¹⁹⁶⁹ is an apocalyptic number.

It is an amenable number.

661969 is a deficient number, since it is larger than the sum of its proper divisors (163439).

661969 is a wasteful number, since it uses less digits than its factorization.

661969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8615.

The product of its digits is 17496, while the sum is 37.

The square root of 661969 is about 813.6147737105. The cubic root of 661969 is about 87.1523731306.

The spelling of 661969 in words is "six hundred sixty-one thousand, nine hundred sixty-nine".