78206421 has 8 divisors (see below), whose sum is σ = 105308064. Its totient is φ = 51621200.

The previous prime is 78206399. The next prime is 78206423. The reversal of 78206421 is 12460287.

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 78206421 - 2⁶ = 78206357 is a prime.

It is a super-2 number, since 2×78206421² = 12232488571258482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78206423) 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, 128751 + ... + 129356.

It is an arithmetic number, because the mean of its divisors is an integer number (13163508).

Almost surely, 2^78206421 is an apocalyptic number.

It is an amenable number.

78206421 is a deficient number, since it is larger than the sum of its proper divisors (27101643).

78206421 is a wasteful number, since it uses less digits than its factorization.

78206421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258211.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 78206421 is about 8843.4394327094. The cubic root of 78206421 is about 427.6424449223.

It can be divided in two parts, 7820 and 6421, that added together give a palindrome (14241).

The spelling of 78206421 in words is "seventy-eight million, two hundred six thousand, four hundred twenty-one".