21101972 has 12 divisors (see below), whose sum is σ = 37049376. Its totient is φ = 10516440.

The previous prime is 21101963. The next prime is 21102023. The reversal of 21101972 is 27910112.

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 3 ways as a sum of consecutive naturals, for example, 7238 + ... + 9725.

It is an arithmetic number, because the mean of its divisors is an integer number (3087448).

Almost surely, 2^21101972 is an apocalyptic number.

It is an amenable number.

21101972 is a deficient number, since it is larger than the sum of its proper divisors (15947404).

21101972 is a wasteful number, since it uses less digits than its factorization.

21101972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17278 (or 17276 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 21101972 is about 4593.6882784969. The cubic root of 21101972 is about 276.3382571208.

It can be divided in two parts, 21 and 101972, that multiplied together give a palindrome (2141412).

The spelling of 21101972 in words is "twenty-one million, one hundred one thousand, nine hundred seventy-two".