620687561 has 16 divisors (see below), whose sum is σ = 725025168. Its totient is φ = 526080000.

The previous prime is 620687539. The next prime is 620687603. The reversal of 620687561 is 165786026.

It can be written as a sum of positive squares in 8 ways, for example, as 223681936 + 397005625 = 14956^2 + 19925^2 .

It is a cyclic number.

It is not a de Polignac number, because 620687561 - 2¹⁰ = 620686537 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (620687461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25190 + ... + 43311.

It is an arithmetic number, because the mean of its divisors is an integer number (45314073).

Almost surely, 2^620687561 is an apocalyptic number.

It is an amenable number.

620687561 is a deficient number, since it is larger than the sum of its proper divisors (104337607).

620687561 is a wasteful number, since it uses less digits than its factorization.

620687561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68572.

The product of its (nonzero) digits is 120960, while the sum is 41.

The square root of 620687561 is about 24913.6019274612. The cubic root of 620687561 is about 853.0169886397.

The spelling of 620687561 in words is "six hundred twenty million, six hundred eighty-seven thousand, five hundred sixty-one".