1621113881 has 2 divisors, whose sum is σ = 1621113882. Its totient is φ = 1621113880.

The previous prime is 1621113811. The next prime is 1621113911. The reversal of 1621113881 is 1883111261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1385030656 + 236083225 = 37216^2 + 15365^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621113881 - 2³⁰ = 547372057 is a prime.

It is a super-2 number, since 2×1621113881² = 5256020430341764322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1621113811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810556940 + 810556941.

It is an arithmetic number, because the mean of its divisors is an integer number (810556941).

Almost surely, 2^1621113881 is an apocalyptic number.

It is an amenable number.

1621113881 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621113881 is an equidigital number, since it uses as much as digits as its factorization.

1621113881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 32.

The square root of 1621113881 is about 40263.0585152196. The cubic root of 1621113881 is about 1174.7294094877.

The spelling of 1621113881 in words is "one billion, six hundred twenty-one million, one hundred thirteen thousand, eight hundred eighty-one".