1656615601 has 4 divisors (see below), whose sum is σ = 1657434100. Its totient is φ = 1655797104.

The previous prime is 1656615589. The next prime is 1656615607. The reversal of 1656615601 is 1065166561.

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

It can be written as a sum of positive squares in 2 ways, for example, as 815673600 + 840942001 = 28560^2 + 28999^2 .

It is a cyclic number.

It is not a de Polignac number, because 1656615601 - 2¹³ = 1656607409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1656615607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 406206 + ... + 410263.

It is an arithmetic number, because the mean of its divisors is an integer number (414358525).

Almost surely, 2^1656615601 is an apocalyptic number.

It is an amenable number.

1656615601 is a deficient number, since it is larger than the sum of its proper divisors (818499).

1656615601 is an equidigital number, since it uses as much as digits as its factorization.

1656615601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 818498.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 1656615601 is about 40701.5429805800. The cubic root of 1656615601 is about 1183.2429230844.

The spelling of 1656615601 in words is "one billion, six hundred fifty-six million, six hundred fifteen thousand, six hundred one".