620403661 has 4 divisors (see below), whose sum is σ = 656898012. Its totient is φ = 583909312.

The previous prime is 620403601. The next prime is 620403673. The reversal of 620403661 is 166304026.

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 412496100 + 207907561 = 20310^2 + 14419^2 .

It is a cyclic number.

It is not a de Polignac number, because 620403661 - 2¹⁵ = 620370893 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 (620403601) 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, 18247150 + ... + 18247183.

It is an arithmetic number, because the mean of its divisors is an integer number (164224503).

Almost surely, 2^620403661 is an apocalyptic number.

It is an amenable number.

620403661 is a deficient number, since it is larger than the sum of its proper divisors (36494351).

620403661 is a wasteful number, since it uses less digits than its factorization.

620403661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36494350.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 620403661 is about 24907.9035850069. The cubic root of 620403661 is about 852.8869132897.

Adding to 620403661 its reverse (166304026), we get a palindrome (786707687).

The spelling of 620403661 in words is "six hundred twenty million, four hundred three thousand, six hundred sixty-one".