21863961 has 48 divisors (see below), whose sum is σ = 38338560. Its totient is φ = 11737440.

The previous prime is 21863957. The next prime is 21863993. The reversal of 21863961 is 16936812.

21863961 is a `hidden beast` number, since 2 + 18 + 639 + 6 + 1 = 666.

It is not a de Polignac number, because 21863961 - 2² = 21863957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21863911) by changing a digit.

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, 114376 + ... + 114566.

It is an arithmetic number, because the mean of its divisors is an integer number (798720).

Almost surely, 2^21863961 is an apocalyptic number.

21863961 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21863961 is a deficient number, since it is larger than the sum of its proper divisors (16474599).

21863961 is a wasteful number, since it uses less digits than its factorization.

21863961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 303 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21863961 is about 4675.8914658063. The cubic root of 21863961 is about 279.6251830056.

The spelling of 21863961 in words is "twenty-one million, eight hundred sixty-three thousand, nine hundred sixty-one".