1661020545 has 16 divisors (see below), whose sum is σ = 2701202112. Its totient is φ = 871354560.

The previous prime is 1661020523. The next prime is 1661020549. The reversal of 1661020545 is 5450201661.

It is not a de Polignac number, because 1661020545 - 2⁸ = 1661020289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1661020549) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 906747 + ... + 908576.

It is an arithmetic number, because the mean of its divisors is an integer number (168825132).

Almost surely, 2^1661020545 is an apocalyptic number.

1661020545 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661020545 is a deficient number, since it is larger than the sum of its proper divisors (1040181567).

1661020545 is a wasteful number, since it uses less digits than its factorization.

1661020545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1815392.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 1661020545 is about 40755.6197965385. The cubic root of 1661020545 is about 1184.2907433001.

The spelling of 1661020545 in words is "one billion, six hundred sixty-one million, twenty thousand, five hundred forty-five".