1656223421 has 2 divisors, whose sum is σ = 1656223422. Its totient is φ = 1656223420.

The previous prime is 1656223409. The next prime is 1656223441. The reversal of 1656223421 is 1243226561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1412707396 + 243516025 = 37586^2 + 15605^2 .

It is a cyclic number.

It is not a de Polignac number, because 1656223421 - 2¹⁴ = 1656207037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1656223441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 828111710 + 828111711.

It is an arithmetic number, because the mean of its divisors is an integer number (828111711).

Almost surely, 2^1656223421 is an apocalyptic number.

It is an amenable number.

1656223421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1656223421 is an equidigital number, since it uses as much as digits as its factorization.

1656223421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 32.

The square root of 1656223421 is about 40696.7249419410. The cubic root of 1656223421 is about 1183.1495437809.

Adding to 1656223421 its reverse (1243226561), we get a palindrome (2899449982).

The spelling of 1656223421 in words is "one billion, six hundred fifty-six million, two hundred twenty-three thousand, four hundred twenty-one".