21931550 has 12 divisors (see below), whose sum is σ = 40792776. Its totient is φ = 8772600.

The previous prime is 21931541. The next prime is 21931561. The reversal of 21931550 is 5513912.

It is a Curzon number.

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 5 ways as a sum of consecutive naturals, for example, 219266 + ... + 219365.

It is an arithmetic number, because the mean of its divisors is an integer number (3399398).

Almost surely, 2^21931550 is an apocalyptic number.

21931550 is a deficient number, since it is larger than the sum of its proper divisors (18861226).

21931550 is a wasteful number, since it uses less digits than its factorization.

21931550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 438643 (or 438638 counting only the distinct ones).

The product of its (nonzero) digits is 1350, while the sum is 26.

The square root of 21931550 is about 4683.1132807140. The cubic root of 21931550 is about 279.9130257077.

The spelling of 21931550 in words is "twenty-one million, nine hundred thirty-one thousand, five hundred fifty".