21169251 has 6 divisors (see below), whose sum is σ = 30577820. Its totient is φ = 14112828.

The previous prime is 21169241. The next prime is 21169261. The reversal of 21169251 is 15296112.

It is an interprime number because it is at equal distance from previous prime (21169241) and next prime (21169261).

It is not a de Polignac number, because 21169251 - 2⁵ = 21169219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21169241) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1176061 + ... + 1176078.

Almost surely, 2^21169251 is an apocalyptic number.

21169251 is a deficient number, since it is larger than the sum of its proper divisors (9408569).

21169251 is a wasteful number, since it uses less digits than its factorization.

21169251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2352145 (or 2352142 counting only the distinct ones).

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

The square root of 21169251 is about 4601.0054335982. The cubic root of 21169251 is about 276.6316268264.

The spelling of 21169251 in words is "twenty-one million, one hundred sixty-nine thousand, two hundred fifty-one".