647642421 has 24 divisors (see below), whose sum is σ = 1022471424. Its totient is φ = 393252480.

The previous prime is 647642407. The next prime is 647642423. The reversal of 647642421 is 124246746.

647642421 is a `hidden beast` number, since 6 + 4 + 7 + 642 + 4 + 2 + 1 = 666.

It is not a de Polignac number, because 647642421 - 2⁷ = 647642293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647642423) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 63531 + ... + 73016.

It is an arithmetic number, because the mean of its divisors is an integer number (42602976).

Almost surely, 2^647642421 is an apocalyptic number.

It is an amenable number.

647642421 is a deficient number, since it is larger than the sum of its proper divisors (374829003).

647642421 is a wasteful number, since it uses less digits than its factorization.

647642421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136601 (or 136598 counting only the distinct ones).

The product of its digits is 64512, while the sum is 36.

The square root of 647642421 is about 25448.8196386394. The cubic root of 647642421 is about 865.1905406260.

The spelling of 647642421 in words is "six hundred forty-seven million, six hundred forty-two thousand, four hundred twenty-one".