1621581113 has 2 divisors, whose sum is σ = 1621581114. Its totient is φ = 1621581112.

The previous prime is 1621581109. The next prime is 1621581131. The reversal of 1621581113 is 3111851261.

Together with next prime (1621581131) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1032208384 + 589372729 = 32128^2 + 24277^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621581113 - 2² = 1621581109 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1621581133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810790556 + 810790557.

It is an arithmetic number, because the mean of its divisors is an integer number (810790557).

Almost surely, 2^1621581113 is an apocalyptic number.

It is an amenable number.

1621581113 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621581113 is an equidigital number, since it uses as much as digits as its factorization.

1621581113 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 29.

The square root of 1621581113 is about 40268.8603389766. The cubic root of 1621581113 is about 1174.8422575023.

The spelling of 1621581113 in words is "one billion, six hundred twenty-one million, five hundred eighty-one thousand, one hundred thirteen".