1661531 has 8 divisors (see below), whose sum is σ = 1763280. Its totient is φ = 1561248.

The previous prime is 1661519. The next prime is 1661549. The reversal of 1661531 is 1351661.

It is a happy number.

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 1661531 - 2¹⁰ = 1660507 is a prime.

It is a super-2 number, since 2×1661531² = 5521370527922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1661497 and 1661506.

It is not an unprimeable number, because it can be changed into a prime (1661431) 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, 2705 + ... + 3261.

It is an arithmetic number, because the mean of its divisors is an integer number (220410).

2^1661531 is an apocalyptic number.

1661531 is a deficient number, since it is larger than the sum of its proper divisors (101749).

1661531 is a wasteful number, since it uses less digits than its factorization.

1661531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733.

The product of its digits is 540, while the sum is 23.

The square root of 1661531 is about 1289.0038789701. The cubic root of 1661531 is about 118.4412047281.

The spelling of 1661531 in words is "one million, six hundred sixty-one thousand, five hundred thirty-one".