195216021 has 128 divisors (see below), whose sum is σ = 402554880. Its totient is φ = 90201600.

The previous prime is 195216017. The next prime is 195216029. The reversal of 195216021 is 120612591.

195216021 is a `hidden beast` number, since 1 + 9 + 52 + 1 + 602 + 1 = 666.

It is not a de Polignac number, because 195216021 - 2² = 195216017 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (195216029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 837721 + ... + 837953.

It is an arithmetic number, because the mean of its divisors is an integer number (3144960).

Almost surely, 2^195216021 is an apocalyptic number.

195216021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

195216021 is an abundant number, since it is smaller than the sum of its proper divisors (207338859).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

195216021 is a wasteful number, since it uses less digits than its factorization.

195216021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 195216021 is about 13971.9726953641. The cubic root of 195216021 is about 580.1030544191.

The spelling of 195216021 in words is "one hundred ninety-five million, two hundred sixteen thousand, twenty-one".