751671721 has 4 divisors (see below), whose sum is σ = 759421012. Its totient is φ = 743922432.

The previous prime is 751671719. The next prime is 751671731. The reversal of 751671721 is 127176157.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127176157 = 631 ⋅201547.

It can be written as a sum of positive squares in 2 ways, for example, as 112593321 + 639078400 = 10611^2 + 25280^2 .

It is a cyclic number.

It is not a de Polignac number, because 751671721 - 2¹ = 751671719 is a prime.

It is a super-2 number, since 2×751671721² = 1130020752302203682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (751671731) 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, 3874500 + ... + 3874693.

It is an arithmetic number, because the mean of its divisors is an integer number (189855253).

Almost surely, 2^751671721 is an apocalyptic number.

It is an amenable number.

751671721 is a deficient number, since it is larger than the sum of its proper divisors (7749291).

751671721 is an equidigital number, since it uses as much as digits as its factorization.

751671721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7749290.

The product of its digits is 20580, while the sum is 37.

The square root of 751671721 is about 27416.6321965335. The cubic root of 751671721 is about 909.2348440737.

The spelling of 751671721 in words is "seven hundred fifty-one million, six hundred seventy-one thousand, seven hundred twenty-one".