651051721 has 4 divisors (see below), whose sum is σ = 651251200. Its totient is φ = 650852244.

The previous prime is 651051697. The next prime is 651051727. The reversal of 651051721 is 127150156.

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 651051721 - 2¹⁷ = 650920649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 651051721.

It is not an unprimeable number, because it can be changed into a prime (651051727) 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, 94761 + ... + 101398.

It is an arithmetic number, because the mean of its divisors is an integer number (162812800).

Almost surely, 2^651051721 is an apocalyptic number.

It is an amenable number.

651051721 is a deficient number, since it is larger than the sum of its proper divisors (199479).

651051721 is a wasteful number, since it uses less digits than its factorization.

651051721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199478.

The product of its (nonzero) digits is 2100, while the sum is 28.

The square root of 651051721 is about 25515.7151771217. The cubic root of 651051721 is about 866.7060545380.

The spelling of 651051721 in words is "six hundred fifty-one million, fifty-one thousand, seven hundred twenty-one".