213857681 has 8 divisors (see below), whose sum is σ = 219265704. Its totient is φ = 208458880.

The previous prime is 213857663. The next prime is 213857689. The reversal of 213857681 is 186758312.

It can be written as a sum of positive squares in 4 ways, for example, as 17297281 + 196560400 = 4159^2 + 14020^2 .

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 213857681 - 2¹⁴ = 213841297 is a prime.

It is a super-2 number, since 2×213857681² = 91470215445395522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is not an unprimeable number, because it can be changed into a prime (213857689) 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, 89555 + ... + 91911.

It is an arithmetic number, because the mean of its divisors is an integer number (27408213).

Almost surely, 2^213857681 is an apocalyptic number.

It is an amenable number.

213857681 is a deficient number, since it is larger than the sum of its proper divisors (5408023).

213857681 is a wasteful number, since it uses less digits than its factorization.

213857681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4611.

The product of its digits is 80640, while the sum is 41.

The square root of 213857681 is about 14623.8736660298. The cubic root of 213857681 is about 598.0097769493.

The spelling of 213857681 in words is "two hundred thirteen million, eight hundred fifty-seven thousand, six hundred eighty-one".