81900007 has 4 divisors (see below), whose sum is σ = 93600016. Its totient is φ = 70200000.

The previous prime is 81899977. The next prime is 81900017. The reversal of 81900007 is 70000918.

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

It is a cyclic number.

It is not a de Polignac number, because 81900007 - 2⁷ = 81899879 is a prime.

It is a super-2 number, since 2×81900007² = 13415222293200098, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81900017) 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, 5849994 + ... + 5850007.

It is an arithmetic number, because the mean of its divisors is an integer number (23400004).

Almost surely, 2^81900007 is an apocalyptic number.

81900007 is a deficient number, since it is larger than the sum of its proper divisors (11700009).

81900007 is a wasteful number, since it uses less digits than its factorization.

81900007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11700008.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 81900007 is about 9049.8622641452. The cubic root of 81900007 is about 434.2714841715.

The spelling of 81900007 in words is "eighty-one million, nine hundred thousand, seven".