655016021 has 4 divisors (see below), whose sum is σ = 714562944. Its totient is φ = 595469100.

The previous prime is 655016009. The next prime is 655016027. The reversal of 655016021 is 120610556.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 655016021 - 2¹⁸ = 654753877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655016027) 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, 29773445 + ... + 29773466.

It is an arithmetic number, because the mean of its divisors is an integer number (178640736).

Almost surely, 2^655016021 is an apocalyptic number.

It is an amenable number.

655016021 is a deficient number, since it is larger than the sum of its proper divisors (59546923).

655016021 is a wasteful number, since it uses less digits than its factorization.

655016021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59546922.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 655016021 is about 25593.2807783606. The cubic root of 655016021 is about 868.4616408809.

Adding to 655016021 its reverse (120610556), we get a palindrome (775626577).

The spelling of 655016021 in words is "six hundred fifty-five million, sixteen thousand, twenty-one".