21509950 has 96 divisors (see below), whose sum is σ = 51568128. Its totient is φ = 6480000.

The previous prime is 21509941. The next prime is 21509963. The reversal of 21509950 is 5990512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 142375 + ... + 142525.

It is an arithmetic number, because the mean of its divisors is an integer number (537168).

Almost surely, 2^21509950 is an apocalyptic number.

21509950 is an abundant number, since it is smaller than the sum of its proper divisors (30058178).

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

21509950 is a wasteful number, since it uses less digits than its factorization.

21509950 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 4050, while the sum is 31.

The square root of 21509950 is about 4637.8820597337. The cubic root of 21509950 is about 278.1077769918.

It can be divided in two parts, 2150 and 9950, that added together give a square (12100 = 110²).

The spelling of 21509950 in words is "twenty-one million, five hundred nine thousand, nine hundred fifty".