20381951 has 4 divisors (see below), whose sum is σ = 20399400. Its totient is φ = 20364504.

The previous prime is 20381947. The next prime is 20381971. The reversal of 20381951 is 15918302.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15918302 = 2 ⋅7959151.

It is a cyclic number.

It is not a de Polignac number, because 20381951 - 2² = 20381947 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 (20381941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6836 + ... + 9353.

It is an arithmetic number, because the mean of its divisors is an integer number (5099850).

Almost surely, 2^20381951 is an apocalyptic number.

20381951 is a deficient number, since it is larger than the sum of its proper divisors (17449).

20381951 is a wasteful number, since it uses less digits than its factorization.

20381951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17448.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 20381951 is about 4514.6374162274. The cubic root of 20381951 is about 273.1588345205.

The spelling of 20381951 in words is "twenty million, three hundred eighty-one thousand, nine hundred fifty-one".