30726721 has 4 divisors (see below), whose sum is σ = 30806100. Its totient is φ = 30647344.

The previous prime is 30726713. The next prime is 30726727. The reversal of 30726721 is 12762703.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12762703 = 59 ⋅216317.

It can be written as a sum of positive squares in 2 ways, for example, as 16769025 + 13957696 = 4095^2 + 3736^2 .

It is a cyclic number.

It is not a de Polignac number, because 30726721 - 2³ = 30726713 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 30726721.

It is not an unprimeable number, because it can be changed into a prime (30726727) 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, 39106 + ... + 39883.

It is an arithmetic number, because the mean of its divisors is an integer number (7701525).

Almost surely, 2^30726721 is an apocalyptic number.

It is an amenable number.

30726721 is a deficient number, since it is larger than the sum of its proper divisors (79379).

30726721 is an equidigital number, since it uses as much as digits as its factorization.

30726721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79378.

The product of its (nonzero) digits is 3528, while the sum is 28.

The square root of 30726721 is about 5543.1688590553. The cubic root of 30726721 is about 313.2122497543.

It can be divided in two parts, 307 and 26721, that added together give a triangular number (27028 = T₂₃₂).

The spelling of 30726721 in words is "thirty million, seven hundred twenty-six thousand, seven hundred twenty-one".