20972421 has 12 divisors (see below), whose sum is σ = 30382560. Its totient is φ = 13940520.

The previous prime is 20972417. The next prime is 20972429. The reversal of 20972421 is 12427902.

It is not a de Polignac number, because 20972421 - 2² = 20972417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20972429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15 + ... + 6476.

It is an arithmetic number, because the mean of its divisors is an integer number (2531880).

Almost surely, 2^20972421 is an apocalyptic number.

It is an amenable number.

20972421 is a deficient number, since it is larger than the sum of its proper divisors (9410139).

20972421 is a wasteful number, since it uses less digits than its factorization.

20972421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6856 (or 6853 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 20972421 is about 4579.5655907520. The cubic root of 20972421 is about 275.7715895385.

The spelling of 20972421 in words is "twenty million, nine hundred seventy-two thousand, four hundred twenty-one".