81949040 has 40 divisors (see below), whose sum is σ = 193387920. Its totient is φ = 32288256.

The previous prime is 81949019. The next prime is 81949051. The reversal of 81949040 is 4094918.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2285 + ... + 13004.

It is an arithmetic number, because the mean of its divisors is an integer number (4834698).

Almost surely, 2^81949040 is an apocalyptic number.

81949040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81949040 is an abundant number, since it is smaller than the sum of its proper divisors (111438880).

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

81949040 is a wasteful number, since it uses less digits than its factorization.

81949040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15369 (or 15363 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 81949040 is about 9052.5709055494. The cubic root of 81949040 is about 434.3581320503.

The spelling of 81949040 in words is "eighty-one million, nine hundred forty-nine thousand, forty".