21125907 has 32 divisors (see below), whose sum is σ = 34594560. Its totient is φ = 12634560.

The previous prime is 21125887. The next prime is 21125933. The reversal of 21125907 is 70952112.

It is not a de Polignac number, because 21125907 - 2⁶ = 21125843 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21125107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24223 + ... + 25079.

It is an arithmetic number, because the mean of its divisors is an integer number (1081080).

Almost surely, 2^21125907 is an apocalyptic number.

21125907 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21125907 is a deficient number, since it is larger than the sum of its proper divisors (13468653).

21125907 is a wasteful number, since it uses less digits than its factorization.

21125907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960 (or 954 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21125907 is about 4596.2927452459. The cubic root of 21125907 is about 276.4426969183.

The spelling of 21125907 in words is "twenty-one million, one hundred twenty-five thousand, nine hundred seven".