661020605 has 16 divisors (see below), whose sum is σ = 959869440. Its totient is φ = 426607872.

The previous prime is 661020587. The next prime is 661020617. The reversal of 661020605 is 506020166.

It is a cyclic number.

It is not a de Polignac number, because 661020605 - 2⁶ = 661020541 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 554885 + ... + 556074.

It is an arithmetic number, because the mean of its divisors is an integer number (59991840).

Almost surely, 2^661020605 is an apocalyptic number.

It is an amenable number.

661020605 is a deficient number, since it is larger than the sum of its proper divisors (298848835).

661020605 is a wasteful number, since it uses less digits than its factorization.

661020605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110988.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 661020605 is about 25710.3209820492. The cubic root of 661020605 is about 871.1073252041.

The spelling of 661020605 in words is "six hundred sixty-one million, twenty thousand, six hundred five".