656212015421 has 4 divisors (see below), whose sum is σ = 656215965372. Its totient is φ = 656208065472.

The previous prime is 656212015411. The next prime is 656212015441. The reversal of 656212015421 is 124510212656.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 186288055321 + 469923960100 = 431611^2 + 685510^2 .

It is a cyclic number.

It is not a de Polignac number, because 656212015421 - 2⁶ = 656212015357 is a prime.

It is a super-2 number, since 2×656212015421² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656212015411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1714310 + ... + 2061863.

It is an arithmetic number, because the mean of its divisors is an integer number (164053991343).

Almost surely, 2^656212015421 is an apocalyptic number.

It is an amenable number.

656212015421 is a deficient number, since it is larger than the sum of its proper divisors (3949951).

656212015421 is a wasteful number, since it uses less digits than its factorization.

656212015421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3949950.

The product of its (nonzero) digits is 28800, while the sum is 35.

The spelling of 656212015421 in words is "six hundred fifty-six billion, two hundred twelve million, fifteen thousand, four hundred twenty-one".