21620535 has 16 divisors (see below), whose sum is σ = 35161440. Its totient is φ = 11341440.

The previous prime is 21620531. The next prime is 21620561. The reversal of 21620535 is 53502612.

It is not a de Polignac number, because 21620535 - 2² = 21620531 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21620531) 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, 10900 + ... + 12729.

It is an arithmetic number, because the mean of its divisors is an integer number (2197590).

Almost surely, 2^21620535 is an apocalyptic number.

21620535 is a deficient number, since it is larger than the sum of its proper divisors (13540905).

21620535 is a wasteful number, since it uses less digits than its factorization.

21620535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23698.

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21620535 is about 4649.7887048768. The cubic root of 21620535 is about 278.5835567181.

It can be divided in two parts, 21620 and 535, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21620535 in words is "twenty-one million, six hundred twenty thousand, five hundred thirty-five".