6401655021 has 16 divisors (see below), whose sum is σ = 8952817536. Its totient is φ = 4061054976.

The previous prime is 6401655019. The next prime is 6401655037. The reversal of 6401655021 is 1205561046.

It is not a de Polignac number, because 6401655021 - 2¹ = 6401655019 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6401655021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6401655041) 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, 227040 + ... + 253673.

It is an arithmetic number, because the mean of its divisors is an integer number (559551096).

Almost surely, 2^6401655021 is an apocalyptic number.

It is an amenable number.

6401655021 is a deficient number, since it is larger than the sum of its proper divisors (2551162515).

6401655021 is a wasteful number, since it uses less digits than its factorization.

6401655021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 480932.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 6401655021 is about 80010.3432126122. The cubic root of 6401655021 is about 1856.7955597975.

The spelling of 6401655021 in words is "six billion, four hundred one million, six hundred fifty-five thousand, twenty-one".