78121440 has 72 divisors (see below), whose sum is σ = 266594328. Its totient is φ = 20832000.

The previous prime is 78121429. The next prime is 78121453. The reversal of 78121440 is 4412187.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×78121440² = 12205918775347200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 25686 + ... + 28565.

It is an arithmetic number, because the mean of its divisors is an integer number (3702699).

Almost surely, 2^78121440 is an apocalyptic number.

It is an amenable number.

78121440 is an abundant number, since it is smaller than the sum of its proper divisors (188472888).

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

78121440 is a wasteful number, since it uses less digits than its factorization.

78121440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54272 (or 54261 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 78121440 is about 8838.6333785263. The cubic root of 78121440 is about 427.4874932219.

The spelling of 78121440 in words is "seventy-eight million, one hundred twenty-one thousand, four hundred forty".