21906837 has 12 divisors (see below), whose sum is σ = 32089824. Its totient is φ = 14398440.

The previous prime is 21906821. The next prime is 21906839. The reversal of 21906837 is 73860912.

It is not a de Polignac number, because 21906837 - 2⁴ = 21906821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21906839) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16503 + ... + 17780.

It is an arithmetic number, because the mean of its divisors is an integer number (2674152).

Almost surely, 2^21906837 is an apocalyptic number.

It is an amenable number.

21906837 is a deficient number, since it is larger than the sum of its proper divisors (10182987).

21906837 is a wasteful number, since it uses less digits than its factorization.

21906837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34360 (or 34357 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21906837 is about 4680.4740144562. The cubic root of 21906837 is about 279.8078486075.

The spelling of 21906837 in words is "twenty-one million, nine hundred six thousand, eight hundred thirty-seven".