21801916 has 12 divisors (see below), whose sum is σ = 38800440. Its totient is φ = 10716080.

The previous prime is 21801893. The next prime is 21801929. The reversal of 21801916 is 61910812.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45955 + ... + 46426.

It is an arithmetic number, because the mean of its divisors is an integer number (3233370).

Almost surely, 2^21801916 is an apocalyptic number.

It is an amenable number.

21801916 is a deficient number, since it is larger than the sum of its proper divisors (16998524).

21801916 is a wasteful number, since it uses less digits than its factorization.

21801916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92444 (or 92442 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 21801916 is about 4669.2521885201. The cubic root of 21801916 is about 279.3604279660.

It can be divided in two parts, 2180 and 1916, that added together give a 12-th power (4096 = 2¹²).

The spelling of 21801916 in words is "twenty-one million, eight hundred one thousand, nine hundred sixteen".