164987921 has 16 divisors (see below), whose sum is σ = 199910400. Its totient is φ = 133151040.

The previous prime is 164987917. The next prime is 164987939. The reversal of 164987921 is 129789461.

It is a cyclic number.

It is not a de Polignac number, because 164987921 - 2² = 164987917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (164987951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2246 + ... + 18303.

It is an arithmetic number, because the mean of its divisors is an integer number (12494400).

Almost surely, 2^164987921 is an apocalyptic number.

It is an amenable number.

164987921 is a deficient number, since it is larger than the sum of its proper divisors (34922479).

164987921 is a wasteful number, since it uses less digits than its factorization.

164987921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20624.

The product of its digits is 217728, while the sum is 47.

The square root of 164987921 is about 12844.7623956226. The cubic root of 164987921 is about 548.4672708806.

The spelling of 164987921 in words is "one hundred sixty-four million, nine hundred eighty-seven thousand, nine hundred twenty-one".