81978435 has 96 divisors (see below), whose sum is σ = 180610560. Its totient is φ = 33408000.

The previous prime is 81978431. The next prime is 81978443. The reversal of 81978435 is 53487918.

It is not a de Polignac number, because 81978435 - 2² = 81978431 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81978431) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 204235 + ... + 204635.

It is an arithmetic number, because the mean of its divisors is an integer number (1881360).

Almost surely, 2^81978435 is an apocalyptic number.

81978435 is an abundant number, since it is smaller than the sum of its proper divisors (98632125).

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

81978435 is a wasteful number, since it uses less digits than its factorization.

81978435 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489 (or 486 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 81978435 is about 9054.1943319105. The cubic root of 81978435 is about 434.4100603828.

The spelling of 81978435 in words is "eighty-one million, nine hundred seventy-eight thousand, four hundred thirty-five".