21151279 has 4 divisors (see below), whose sum is σ = 21229600. Its totient is φ = 21072960.

The previous prime is 21151271. The next prime is 21151303. The reversal of 21151279 is 97215112.

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

It is not a de Polignac number, because 21151279 - 2³ = 21151271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151271) 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, 38754 + ... + 39295.

It is an arithmetic number, because the mean of its divisors is an integer number (5307400).

Almost surely, 2^21151279 is an apocalyptic number.

21151279 is a deficient number, since it is larger than the sum of its proper divisors (78321).

21151279 is an equidigital number, since it uses as much as digits as its factorization.

21151279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78320.

The product of its digits is 1260, while the sum is 28.

The square root of 21151279 is about 4599.0519675255. The cubic root of 21151279 is about 276.5533209355.

The spelling of 21151279 in words is "twenty-one million, one hundred fifty-one thousand, two hundred seventy-nine".