78154421 has 2 divisors, whose sum is σ = 78154422. Its totient is φ = 78154420.

The previous prime is 78154411. The next prime is 78154451. The reversal of 78154421 is 12445187.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59136100 + 19018321 = 7690^2 + 4361^2 .

It is an emirp because it is prime and its reverse (12445187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78154421 - 2⁶ = 78154357 is a prime.

It is a super-2 number, since 2×78154421² = 12216227043690482, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78154411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39077210 + 39077211.

It is an arithmetic number, because the mean of its divisors is an integer number (39077211).

Almost surely, 2^78154421 is an apocalyptic number.

It is an amenable number.

78154421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78154421 is an equidigital number, since it uses as much as digits as its factorization.

78154421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8960, while the sum is 32.

The square root of 78154421 is about 8840.4989112606. The cubic root of 78154421 is about 427.5476430834.

The spelling of 78154421 in words is "seventy-eight million, one hundred fifty-four thousand, four hundred twenty-one".