21020587 has 8 divisors (see below), whose sum is σ = 24101856. Its totient is φ = 17958912.

The previous prime is 21020581. The next prime is 21020591. The reversal of 21020587 is 78502012.

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 21020587 - 2¹¹ = 21018539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020581) 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, 2518 + ... + 6955.

It is an arithmetic number, because the mean of its divisors is an integer number (3012732).

Almost surely, 2^21020587 is an apocalyptic number.

21020587 is a deficient number, since it is larger than the sum of its proper divisors (3081269).

21020587 is an equidigital number, since it uses as much as digits as its factorization.

21020587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9797.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21020587 is about 4584.8213705661. The cubic root of 21020587 is about 275.9825437045.

Adding to 21020587 its reverse (78502012), we get a palindrome (99522599).

It can be divided in two parts, 210 and 20587, that multiplied together give a triangular number (4323270 = T₂₉₄₀).

The spelling of 21020587 in words is "twenty-one million, twenty thousand, five hundred eighty-seven".