21561950 has 24 divisors (see below), whose sum is σ = 42466032. Its totient is φ = 8117120.

The previous prime is 21561949. The next prime is 21561997. The reversal of 21561950 is 5916512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11834 + ... + 13533.

It is an arithmetic number, because the mean of its divisors is an integer number (1769418).

Almost surely, 2^21561950 is an apocalyptic number.

21561950 is a deficient number, since it is larger than the sum of its proper divisors (20904082).

21561950 is a wasteful number, since it uses less digits than its factorization.

21561950 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25396 (or 25391 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 29.

The square root of 21561950 is about 4643.4846828648. The cubic root of 21561950 is about 278.3317038482.

The spelling of 21561950 in words is "twenty-one million, five hundred sixty-one thousand, nine hundred fifty".