64111781 has 2 divisors, whose sum is σ = 64111782. Its totient is φ = 64111780.

The previous prime is 64111771. The next prime is 64111783. The reversal of 64111781 is 18711146.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57304900 + 6806881 = 7570^2 + 2609^2 .

It is a cyclic number.

It is not a de Polignac number, because 64111781 - 2²² = 59917477 is a prime.

It is a super-2 number, since 2×64111781² = 8220640925983922, which contains 22 as substring.

Together with 64111783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64111783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32055890 + 32055891.

It is an arithmetic number, because the mean of its divisors is an integer number (32055891).

Almost surely, 2^64111781 is an apocalyptic number.

It is an amenable number.

64111781 is a deficient number, since it is larger than the sum of its proper divisors (1).

64111781 is an equidigital number, since it uses as much as digits as its factorization.

64111781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 29.

The square root of 64111781 is about 8006.9832646259. The cubic root of 64111781 is about 400.2327416354.

It can be divided in two parts, 6411 and 1781, that added together give a 13-th power (8192 = 2¹³).

The spelling of 64111781 in words is "sixty-four million, one hundred eleven thousand, seven hundred eighty-one".