78409551 has 8 divisors (see below), whose sum is σ = 114050304. Its totient is φ = 47520920.

The previous prime is 78409469. The next prime is 78409577. The reversal of 78409551 is 15590487.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78409551 - 2⁹ = 78409039 is a prime.

It is a super-2 number, since 2×78409551² = 12296115376043202, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78409651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1187991 + ... + 1188056.

It is an arithmetic number, because the mean of its divisors is an integer number (14256288).

Almost surely, 2^78409551 is an apocalyptic number.

78409551 is a deficient number, since it is larger than the sum of its proper divisors (35640753).

78409551 is a wasteful number, since it uses less digits than its factorization.

78409551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2376061.

The product of its (nonzero) digits is 50400, while the sum is 39.

The square root of 78409551 is about 8854.9167697952. The cubic root of 78409551 is about 428.0123715380.

It can be divided in two parts, 7840 and 9551, that added together give a triangular number (17391 = T₁₈₆).

The spelling of 78409551 in words is "seventy-eight million, four hundred nine thousand, five hundred fifty-one".