21279601 has 16 divisors (see below), whose sum is σ = 25763200. Its totient is φ = 17169408.

The previous prime is 21279581. The next prime is 21279611. The reversal of 21279601 is 10697212.

It is a happy number.

It is a 3-Lehmer number, since φ(21279601) divides (21279601-1)³.

It is a cyclic number.

It is not a de Polignac number, because 21279601 - 2¹³ = 21271409 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21279601.

It is not an unprimeable number, because it can be changed into a prime (21279611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25255 + ... + 26083.

It is an arithmetic number, because the mean of its divisors is an integer number (1610200).

Almost surely, 2^21279601 is an apocalyptic number.

It is an amenable number.

21279601 is a deficient number, since it is larger than the sum of its proper divisors (4483599).

21279601 is a wasteful number, since it uses less digits than its factorization.

21279601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1048.

The product of its (nonzero) digits is 1512, while the sum is 28.

The square root of 21279601 is about 4612.9817905559. The cubic root of 21279601 is about 277.1114644789. Note that the first 3 decimals are identical.

The spelling of 21279601 in words is "twenty-one million, two hundred seventy-nine thousand, six hundred one".