215684993 has 4 divisors (see below), whose sum is σ = 218904240. Its totient is φ = 212465748.

The previous prime is 215684983. The next prime is 215685013. The reversal of 215684993 is 399486512.

215684993 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 215684993 - 2²² = 211490689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215684983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1609523 + ... + 1609656.

It is an arithmetic number, because the mean of its divisors is an integer number (54726060).

Almost surely, 2^215684993 is an apocalyptic number.

It is an amenable number.

215684993 is a deficient number, since it is larger than the sum of its proper divisors (3219247).

215684993 is an equidigital number, since it uses as much as digits as its factorization.

215684993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3219246.

The product of its digits is 466560, while the sum is 47.

The square root of 215684993 is about 14686.2177908405. The cubic root of 215684993 is about 599.7081849482.

The spelling of 215684993 in words is "two hundred fifteen million, six hundred eighty-four thousand, nine hundred ninety-three".