216413721 has 16 divisors (see below), whose sum is σ = 321332800. Its totient is φ = 143951904.

The previous prime is 216413719. The next prime is 216413741. The reversal of 216413721 is 127314612.

216413721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 216413721 - 2¹ = 216413719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216413741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3570 + ... + 21108.

It is an arithmetic number, because the mean of its divisors is an integer number (20083300).

Almost surely, 2^216413721 is an apocalyptic number.

It is an amenable number.

216413721 is a deficient number, since it is larger than the sum of its proper divisors (104919079).

216413721 is a wasteful number, since it uses less digits than its factorization.

216413721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18005 (or 17999 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 216413721 is about 14711.0067976329. The cubic root of 216413721 is about 600.3828306825.

The spelling of 216413721 in words is "two hundred sixteen million, four hundred thirteen thousand, seven hundred twenty-one".