78291840 has 192 divisors, whose sum is σ = 275118480. Its totient is φ = 18923520.

The previous prime is 78291803. The next prime is 78291841. The reversal of 78291840 is 4819287.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×78291840² = 12259224421171200, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78291841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 232152 + ... + 232488.

Almost surely, 2^78291840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78291840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137559240).

78291840 is an abundant number, since it is smaller than the sum of its proper divisors (196826640).

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

78291840 is a wasteful number, since it uses less digits than its factorization.

78291840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 78291840 is about 8848.2676270556. The cubic root of 78291840 is about 427.7980821806.

It can be divided in two parts, 7829 and 1840, that added together give a palindrome (9669).

The spelling of 78291840 in words is "seventy-eight million, two hundred ninety-one thousand, eight hundred forty".