56721641 has 4 divisors (see below), whose sum is σ = 56880000. Its totient is φ = 56563284.

The previous prime is 56721589. The next prime is 56721647. The reversal of 56721641 is 14612765.

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: 14612765 = 5 ⋅2922553.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-56721641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 56721598 and 56721607.

It is not an unprimeable number, because it can be changed into a prime (56721647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 78641 + ... + 79358.

It is an arithmetic number, because the mean of its divisors is an integer number (14220000).

Almost surely, 2^56721641 is an apocalyptic number.

It is an amenable number.

56721641 is a deficient number, since it is larger than the sum of its proper divisors (158359).

56721641 is a wasteful number, since it uses less digits than its factorization.

56721641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158358.

The product of its digits is 10080, while the sum is 32.

The square root of 56721641 is about 7531.3770985126. The cubic root of 56721641 is about 384.2226198466. Note that the first 3 decimals are identical.

The spelling of 56721641 in words is "fifty-six million, seven hundred twenty-one thousand, six hundred forty-one".