78451978 has 32 divisors (see below), whose sum is σ = 133062912. Its totient is φ = 34382400.

The previous prime is 78451949. The next prime is 78451981. The reversal of 78451978 is 87915487.

It is a super-2 number, since 2×78451978² = 12309425704224968, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70575 + ... + 71677.

It is an arithmetic number, because the mean of its divisors is an integer number (4158216).

Almost surely, 2^78451978 is an apocalyptic number.

78451978 is a deficient number, since it is larger than the sum of its proper divisors (54610934).

78451978 is a wasteful number, since it uses less digits than its factorization.

78451978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1230.

The product of its digits is 564480, while the sum is 49.

The square root of 78451978 is about 8857.3121205025. The cubic root of 78451978 is about 428.0895560406.

It can be divided in two parts, 78451 and 978, that multiplied together give a triangular number (76725078 = T₁₂₃₈₇).

The spelling of 78451978 in words is "seventy-eight million, four hundred fifty-one thousand, nine hundred seventy-eight".