81315887040 has 168 divisors, whose sum is σ = 290052038640. Its totient is φ = 21684215808.

The previous prime is 81315887011. The next prime is 81315887057. The reversal of 81315887040 is 4078851318.

It is a happy number.

It is a super-2 number, since 2×81315887040² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 445105 + ... + 600624.

It is an arithmetic number, because the mean of its divisors is an integer number (1726500230).

Almost surely, 2^81315887040 is an apocalyptic number.

81315887040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81315887040 is an abundant number, since it is smaller than the sum of its proper divisors (208736151600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81315887040 is a wasteful number, since it uses less digits than its factorization.

81315887040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1045761 (or 1045739 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 81315887040 in words is "eighty-one billion, three hundred fifteen million, eight hundred eighty-seven thousand, forty".