216021731 has 4 divisors (see below), whose sum is σ = 216214200. Its totient is φ = 215829264.

The previous prime is 216021719. The next prime is 216021749. The reversal of 216021731 is 137120612.

216021731 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.

It is a cyclic number.

It is not a de Polignac number, because 216021731 - 2¹⁸ = 215759587 is a prime.

It is a super-2 number, since 2×216021731² = 93330776528472722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216021697 and 216021706.

It is not an unprimeable number, because it can be changed into a prime (216021331) 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, 94541 + ... + 96798.

It is an arithmetic number, because the mean of its divisors is an integer number (54053550).

Almost surely, 2^216021731 is an apocalyptic number.

216021731 is a deficient number, since it is larger than the sum of its proper divisors (192469).

216021731 is a wasteful number, since it uses less digits than its factorization.

216021731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192468.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 216021731 is about 14697.6777417387. The cubic root of 216021731 is about 600.0201206216.

The spelling of 216021731 in words is "two hundred sixteen million, twenty-one thousand, seven hundred thirty-one".