81897408 has 42 divisors (see below), whose sum is σ = 234745784. Its totient is φ = 27298944.

The previous prime is 81897407. The next prime is 81897437. The reversal of 81897408 is 80479818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81897407) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 70516 + ... + 71667.

Almost surely, 2^81897408 is an apocalyptic number.

It is an amenable number.

81897408 is an abundant number, since it is smaller than the sum of its proper divisors (152848376).

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

81897408 is a wasteful number, since it uses less digits than its factorization.

81897408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142201 (or 142188 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 81897408 is about 9049.7186696604. The cubic root of 81897408 is about 434.2668904254.

The spelling of 81897408 in words is "eighty-one million, eight hundred ninety-seven thousand, four hundred eight".