1616821 has 2 divisors, whose sum is σ = 1616822. Its totient is φ = 1616820.

The previous prime is 1616809. The next prime is 1616827. The reversal of 1616821 is 1286161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1380625 + 236196 = 1175^2 + 486^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1616821 is a prime.

It is a super-2 number, since 2×1616821² = 5228220292082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1616827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 808410 + 808411.

It is an arithmetic number, because the mean of its divisors is an integer number (808411).

2^1616821 is an apocalyptic number.

It is an amenable number.

1616821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1616821 is an equidigital number, since it uses as much as digits as its factorization.

1616821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 25.

The square root of 1616821 is about 1271.5427637323. The cubic root of 1616821 is about 117.3691556930.

The spelling of 1616821 in words is "one million, six hundred sixteen thousand, eight hundred twenty-one".