21520650 has 48 divisors (see below), whose sum is σ = 54398304. Its totient is φ = 5628480.

The previous prime is 21520649. The next prime is 21520651. The reversal of 21520650 is 5602512.

It is an interprime number because it is at equal distance from previous prime (21520649) and next prime (21520651).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21520651) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6597 + ... + 9303.

It is an arithmetic number, because the mean of its divisors is an integer number (1133298).

Almost surely, 2^21520650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21520650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27199152).

21520650 is an abundant number, since it is smaller than the sum of its proper divisors (32877654).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21520650 is a wasteful number, since it uses less digits than its factorization.

21520650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2775 (or 2770 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21520650 is about 4639.0354600930. The cubic root of 21520650 is about 278.1538837149.

The spelling of 21520650 in words is "twenty-one million, five hundred twenty thousand, six hundred fifty".