81620408 has 8 divisors (see below), whose sum is σ = 153038280. Its totient is φ = 40810200.

The previous prime is 81620401. The next prime is 81620411. The reversal of 81620408 is 80402618.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81620401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5101268 + ... + 5101283.

It is an arithmetic number, because the mean of its divisors is an integer number (19129785).

Almost surely, 2^81620408 is an apocalyptic number.

It is an amenable number.

81620408 is a deficient number, since it is larger than the sum of its proper divisors (71417872).

81620408 is a wasteful number, since it uses less digits than its factorization.

81620408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10202557 (or 10202553 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 81620408 is about 9034.4013636765. The cubic root of 81620408 is about 433.7767332586.

It can be divided in two parts, 81620 and 408, that added together give a palindrome (82028).

The spelling of 81620408 in words is "eighty-one million, six hundred twenty thousand, four hundred eight".