166137621 has 32 divisors (see below), whose sum is σ = 245306880. Its totient is φ = 99377664.

The previous prime is 166137619. The next prime is 166137637. The reversal of 166137621 is 126731661.

It is not a de Polignac number, because 166137621 - 2¹ = 166137619 is a prime.

It is a super-2 number, since 2×166137621² = 55203418223079282, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166137641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 426895 + ... + 427283.

It is an arithmetic number, because the mean of its divisors is an integer number (7665840).

Almost surely, 2^166137621 is an apocalyptic number.

It is an amenable number.

166137621 is a deficient number, since it is larger than the sum of its proper divisors (79169259).

166137621 is a wasteful number, since it uses less digits than its factorization.

166137621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685.

The product of its digits is 9072, while the sum is 33.

The square root of 166137621 is about 12889.4383508359. The cubic root of 166137621 is about 549.7383008433.

The spelling of 166137621 in words is "one hundred sixty-six million, one hundred thirty-seven thousand, six hundred twenty-one".