501142721 has 4 divisors (see below), whose sum is σ = 501385392. Its totient is φ = 500900052.

The previous prime is 501142657. The next prime is 501142729. The reversal of 501142721 is 127241105.

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, and also an emirpimes, since its reverse is a distinct semiprime: 127241105 = 5 ⋅25448221.

It is a cyclic number.

It is not a de Polignac number, because 501142721 - 2⁶ = 501142657 is a prime.

It is a super-2 number, since 2×501142721² = 502288053622567682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (501142729) 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 3 ways as a sum of consecutive naturals, for example, 118211 + ... + 122376.

It is an arithmetic number, because the mean of its divisors is an integer number (125346348).

Almost surely, 2^501142721 is an apocalyptic number.

It is an amenable number.

501142721 is a deficient number, since it is larger than the sum of its proper divisors (242671).

501142721 is a wasteful number, since it uses less digits than its factorization.

501142721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242670.

The product of its (nonzero) digits is 560, while the sum is 23.

The square root of 501142721 is about 22386.2172105963. The cubic root of 501142721 is about 794.3047181081.

Adding to 501142721 its reverse (127241105), we get a palindrome (628383826).

The spelling of 501142721 in words is "five hundred one million, one hundred forty-two thousand, seven hundred twenty-one".