64155991 has 2 divisors, whose sum is σ = 64155992. Its totient is φ = 64155990.

The previous prime is 64155937. The next prime is 64156003. The reversal of 64155991 is 19955146.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 64155991 - 2¹³ = 64147799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64155911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32077995 + 32077996.

It is an arithmetic number, because the mean of its divisors is an integer number (32077996).

Almost surely, 2^64155991 is an apocalyptic number.

64155991 is a deficient number, since it is larger than the sum of its proper divisors (1).

64155991 is an equidigital number, since it uses as much as digits as its factorization.

64155991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 40.

The square root of 64155991 is about 8009.7435040081. The cubic root of 64155991 is about 400.3247175749.

The spelling of 64155991 in words is "sixty-four million, one hundred fifty-five thousand, nine hundred ninety-one".