20915951 has 8 divisors (see below), whose sum is σ = 23935104. Its totient is φ = 17904600.

The previous prime is 20915929. The next prime is 20915953. The reversal of 20915951 is 15951902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20915951 - 2²² = 16721647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20915953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5936 + ... + 8778.

It is an arithmetic number, because the mean of its divisors is an integer number (2991888).

Almost surely, 2^20915951 is an apocalyptic number.

20915951 is a deficient number, since it is larger than the sum of its proper divisors (3019153).

20915951 is a wasteful number, since it uses less digits than its factorization.

20915951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3901.

The product of its (nonzero) digits is 4050, while the sum is 32.

The square root of 20915951 is about 4573.3960029720. The cubic root of 20915951 is about 275.5238543557.

The spelling of 20915951 in words is "twenty million, nine hundred fifteen thousand, nine hundred fifty-one".