166420251 has 12 divisors (see below), whose sum is σ = 249288312. Its totient is φ = 110946672.

The previous prime is 166420201. The next prime is 166420273. The reversal of 166420251 is 152024661.

166420251 is a `hidden beast` number, since 16 + 642 + 0 + 2 + 5 + 1 = 666.

It is not a de Polignac number, because 166420251 - 2¹⁸ = 166158107 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (166420201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 342186 + ... + 342671.

It is an arithmetic number, because the mean of its divisors is an integer number (20774026).

Almost surely, 2^166420251 is an apocalyptic number.

166420251 is a deficient number, since it is larger than the sum of its proper divisors (82868061).

166420251 is an frugal number, since it uses more digits than its factorization.

166420251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 684872 (or 684860 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 166420251 is about 12900.3973194627. The cubic root of 166420251 is about 550.0498588409.

The spelling of 166420251 in words is "one hundred sixty-six million, four hundred twenty thousand, two hundred fifty-one".