6401665901 has 2 divisors, whose sum is σ = 6401665902. Its totient is φ = 6401665900.

The previous prime is 6401665867. The next prime is 6401665909. The reversal of 6401665901 is 1095661046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6290869225 + 110796676 = 79315^2 + 10526^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6401665901 is a prime.

It is a super-2 number, since 2×6401665901² = 81962652616052283602, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6401665909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3200832950 + 3200832951.

It is an arithmetic number, because the mean of its divisors is an integer number (3200832951).

Almost surely, 2^6401665901 is an apocalyptic number.

It is an amenable number.

6401665901 is a deficient number, since it is larger than the sum of its proper divisors (1).

6401665901 is an equidigital number, since it uses as much as digits as its factorization.

6401665901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 6401665901 is about 80010.4112037927. The cubic root of 6401665901 is about 1856.7966117090.

The spelling of 6401665901 in words is "six billion, four hundred one million, six hundred sixty-five thousand, nine hundred one".