4020251721 has 4 divisors (see below), whose sum is σ = 5360335632. Its totient is φ = 2680167812.

The previous prime is 4020251717. The next prime is 4020251731. The reversal of 4020251721 is 1271520204.

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 4020251721 - 2² = 4020251717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 4020251691 and 4020251700.

It is not an unprimeable number, because it can be changed into a prime (4020251731) 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, 670041951 + ... + 670041956.

It is an arithmetic number, because the mean of its divisors is an integer number (1340083908).

Almost surely, 2^4020251721 is an apocalyptic number.

It is an amenable number.

4020251721 is a deficient number, since it is larger than the sum of its proper divisors (1340083911).

4020251721 is a wasteful number, since it uses less digits than its factorization.

4020251721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1340083910.

The product of its (nonzero) digits is 1120, while the sum is 24.

The square root of 4020251721 is about 63405.4549782588. The cubic root of 4020251721 is about 1590.0755104363.

Adding to 4020251721 its reverse (1271520204), we get a palindrome (5291771925).

The spelling of 4020251721 in words is "four billion, twenty million, two hundred fifty-one thousand, seven hundred twenty-one".