16251891 has 4 divisors (see below), whose sum is σ = 21669192. Its totient is φ = 10834592.

The previous prime is 16251889. The next prime is 16251913. The reversal of 16251891 is 19815261.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16251891 - 2¹ = 16251889 is a prime.

It is a super-2 number, since 2×16251891² = 528247922151762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16251811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2708646 + ... + 2708651.

It is an arithmetic number, because the mean of its divisors is an integer number (5417298).

Almost surely, 2^16251891 is an apocalyptic number.

16251891 is a deficient number, since it is larger than the sum of its proper divisors (5417301).

16251891 is an equidigital number, since it uses as much as digits as its factorization.

16251891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5417300.

The product of its digits is 4320, while the sum is 33.

The square root of 16251891 is about 4031.3634170092. The cubic root of 16251891 is about 253.2996756223.

The spelling of 16251891 in words is "sixteen million, two hundred fifty-one thousand, eight hundred ninety-one".