641902081 has 2 divisors, whose sum is σ = 641902082. Its totient is φ = 641902080.

The previous prime is 641902049. The next prime is 641902103. The reversal of 641902081 is 180209146.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 467424400 + 174477681 = 21620^2 + 13209^2 .

It is a cyclic number.

It is not a de Polignac number, because 641902081 - 2⁵ = 641902049 is a prime.

It is a super-2 number, since 2×641902081² = 824076563184261122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (641902021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320951040 + 320951041.

It is an arithmetic number, because the mean of its divisors is an integer number (320951041).

Almost surely, 2^641902081 is an apocalyptic number.

It is an amenable number.

641902081 is a deficient number, since it is larger than the sum of its proper divisors (1).

641902081 is an equidigital number, since it uses as much as digits as its factorization.

641902081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 641902081 is about 25335.7865676201. The cubic root of 641902081 is about 862.6267627451.

The spelling of 641902081 in words is "six hundred forty-one million, nine hundred two thousand, eighty-one".