56021561 has 4 divisors (see below), whose sum is σ = 57324432. Its totient is φ = 54718692.

The previous prime is 56021551. The next prime is 56021573. The reversal of 56021561 is 16512065.

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: 16512065 = 5 ⋅3302413.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-56021561 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 56021561.

It is not an unprimeable number, because it can be changed into a prime (56021501) 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, 651371 + ... + 651456.

It is an arithmetic number, because the mean of its divisors is an integer number (14331108).

Almost surely, 2^56021561 is an apocalyptic number.

It is an amenable number.

56021561 is a deficient number, since it is larger than the sum of its proper divisors (1302871).

56021561 is a wasteful number, since it uses less digits than its factorization.

56021561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1302870.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 56021561 is about 7484.7552398191. The cubic root of 56021561 is about 382.6353310986.

The spelling of 56021561 in words is "fifty-six million, twenty-one thousand, five hundred sixty-one".