20667251 has 4 divisors (see below), whose sum is σ = 22546104. Its totient is φ = 18788400.

The previous prime is 20667233. The next prime is 20667277. The reversal of 20667251 is 15276602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20667251 - 2⁶ = 20667187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20667211) 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, 939410 + ... + 939431.

It is an arithmetic number, because the mean of its divisors is an integer number (5636526).

Almost surely, 2^20667251 is an apocalyptic number.

20667251 is a deficient number, since it is larger than the sum of its proper divisors (1878853).

20667251 is a wasteful number, since it uses less digits than its factorization.

20667251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878852.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 20667251 is about 4546.1248333058. The cubic root of 20667251 is about 274.4274633793.

The spelling of 20667251 in words is "twenty million, six hundred sixty-seven thousand, two hundred fifty-one".