21641550 has 48 divisors (see below), whose sum is σ = 61341312. Its totient is φ = 4946400.

The previous prime is 21641537. The next prime is 21641579. The reversal of 21641550 is 5514612.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21641550.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9256 + ... + 11355.

It is an arithmetic number, because the mean of its divisors is an integer number (1277944).

Almost surely, 2^21641550 is an apocalyptic number.

21641550 is an abundant number, since it is smaller than the sum of its proper divisors (39699762).

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

21641550 is a wasteful number, since it uses less digits than its factorization.

21641550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20633 (or 20628 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21641550 is about 4652.0479361245. The cubic root of 21641550 is about 278.6737878749.

The spelling of 21641550 in words is "twenty-one million, six hundred forty-one thousand, five hundred fifty".