451601721 has 12 divisors (see below), whose sum is σ = 654401748. Its totient is φ = 300104064.

The previous prime is 451601701. The next prime is 451601729. The reversal of 451601721 is 127106154.

It is a happy number.

451601721 is a `hidden beast` number, since 4 + 51 + 601 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 185259321 + 266342400 = 13611^2 + 16320^2 .

It is a de Polignac number, because none of the positive numbers 2^k-451601721 is a prime.

It is a super-2 number, since 2×451601721² = 407888228820323682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (451601729) 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 11 ways as a sum of consecutive naturals, for example, 77340 + ... + 82973.

It is an arithmetic number, because the mean of its divisors is an integer number (54533479).

Almost surely, 2^451601721 is an apocalyptic number.

It is an amenable number.

451601721 is a deficient number, since it is larger than the sum of its proper divisors (202800027).

451601721 is a wasteful number, since it uses less digits than its factorization.

451601721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160632 (or 160629 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 451601721 is about 21250.9228270209. The cubic root of 451601721 is about 767.2175512867.

Adding to 451601721 its reverse (127106154), we get a palindrome (578707875).

The spelling of 451601721 in words is "four hundred fifty-one million, six hundred one thousand, seven hundred twenty-one".