21587401 has 8 divisors (see below), whose sum is σ = 24789600. Its totient is φ = 18591840.

The previous prime is 21587389. The next prime is 21587411. The reversal of 21587401 is 10478512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21587401 - 2⁷ = 21587273 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21587401.

It is not an unprimeable number, because it can be changed into a prime (21587411) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51436 + ... + 51853.

It is an arithmetic number, because the mean of its divisors is an integer number (3098700).

Almost surely, 2^21587401 is an apocalyptic number.

It is an amenable number.

21587401 is a deficient number, since it is larger than the sum of its proper divisors (3202199).

21587401 is a wasteful number, since it uses less digits than its factorization.

21587401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103319.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21587401 is about 4646.2243811508. The cubic root of 21587401 is about 278.4411719135.

Subtracting from 21587401 its reverse (10478512), we obtain a square (11108889 = 3333²).

It can be divided in two parts, 2158 and 7401, that added together give a palindrome (9559).

The spelling of 21587401 in words is "twenty-one million, five hundred eighty-seven thousand, four hundred one".