1661666654 has 4 divisors (see below), whose sum is σ = 2492499984. Its totient is φ = 830833326.

The previous prime is 1661666651. The next prime is 1661666687. The reversal of 1661666654 is 4566661661.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×1661666654² = 5522272138031111432, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1661666599 and 1661666608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661666651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415416662 + ... + 415416665.

It is an arithmetic number, because the mean of its divisors is an integer number (623124996).

Almost surely, 2^1661666654 is an apocalyptic number.

1661666654 is a deficient number, since it is larger than the sum of its proper divisors (830833330).

1661666654 is an equidigital number, since it uses as much as digits as its factorization.

1661666654 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830833329.

The product of its digits is 933120, while the sum is 47.

The square root of 1661666654 is about 40763.5456504951. The cubic root of 1661666654 is about 1184.4442797745. Note that the first 3 decimals are identical.

The spelling of 1661666654 in words is "one billion, six hundred sixty-one million, six hundred sixty-six thousand, six hundred fifty-four".