21620534 has 8 divisors (see below), whose sum is σ = 34925520. Its totient is φ = 9978696.

The previous prime is 21620531. The next prime is 21620561. The reversal of 21620534 is 43502612.

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

It is a Curzon number.

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 3 ways as a sum of consecutive naturals, for example, 415754 + ... + 415805.

It is an arithmetic number, because the mean of its divisors is an integer number (4365690).

Almost surely, 2^21620534 is an apocalyptic number.

21620534 is a deficient number, since it is larger than the sum of its proper divisors (13304986).

21620534 is a wasteful number, since it uses less digits than its factorization.

21620534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 831574.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21620534 is about 4649.7885973450. The cubic root of 21620534 is about 278.5835524231.

It can be divided in two parts, 216 and 20534, that multiplied together give a palindrome (4435344).

The spelling of 21620534 in words is "twenty-one million, six hundred twenty thousand, five hundred thirty-four".