1656506399 has 4 divisors (see below), whose sum is σ = 1691751264. Its totient is φ = 1621261536.

The previous prime is 1656506363. The next prime is 1656506407. The reversal of 1656506399 is 9936056561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9936056561 = 683 ⋅14547667.

It is a cyclic number.

It is not a de Polignac number, because 1656506399 - 2⁸ = 1656506143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1656506309) 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, 17622362 + ... + 17622455.

It is an arithmetic number, because the mean of its divisors is an integer number (422937816).

Almost surely, 2^1656506399 is an apocalyptic number.

1656506399 is a deficient number, since it is larger than the sum of its proper divisors (35244865).

1656506399 is an equidigital number, since it uses as much as digits as its factorization.

1656506399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35244864.

The product of its (nonzero) digits is 1312200, while the sum is 50.

The square root of 1656506399 is about 40700.2014614179. The cubic root of 1656506399 is about 1183.2169232220.

The spelling of 1656506399 in words is "one billion, six hundred fifty-six million, five hundred six thousand, three hundred ninety-nine".