81305901 has 12 divisors (see below), whose sum is σ = 121230720. Its totient is φ = 52455240.

The previous prime is 81305899. The next prime is 81305923. The reversal of 81305901 is 10950318.

It is not a de Polignac number, because 81305901 - 2¹ = 81305899 is a prime.

It is a super-2 number, since 2×81305901² = 13221299074843602, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81305941) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 145431 + ... + 145988.

It is an arithmetic number, because the mean of its divisors is an integer number (10102560).

Almost surely, 2^81305901 is an apocalyptic number.

It is an amenable number.

81305901 is a deficient number, since it is larger than the sum of its proper divisors (39924819).

81305901 is a wasteful number, since it uses less digits than its factorization.

81305901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291456 (or 291453 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 81305901 is about 9016.9784850581. The cubic root of 81305901 is about 433.2188604266.

The spelling of 81305901 in words is "eighty-one million, three hundred five thousand, nine hundred one".