81385951 has 4 divisors (see below), whose sum is σ = 82532304. Its totient is φ = 80239600.

The previous prime is 81385939. The next prime is 81385963. The reversal of 81385951 is 15958318.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (81385939) and next prime (81385963).

It is a cyclic number.

It is not a de Polignac number, because 81385951 - 2⁷ = 81385823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81385921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 573070 + ... + 573211.

It is an arithmetic number, because the mean of its divisors is an integer number (20633076).

Almost surely, 2^81385951 is an apocalyptic number.

81385951 is the 4035-th centered decagonal number.

81385951 is a deficient number, since it is larger than the sum of its proper divisors (1146353).

81385951 is a wasteful number, since it uses less digits than its factorization.

81385951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1146352.

The product of its digits is 43200, while the sum is 40.

The square root of 81385951 is about 9021.4162413670. The cubic root of 81385951 is about 433.3609894906.

The spelling of 81385951 in words is "eighty-one million, three hundred eighty-five thousand, nine hundred fifty-one".