20675721 has 16 divisors (see below), whose sum is σ = 30214080. Its totient is φ = 12472320.

The previous prime is 20675719. The next prime is 20675737. The reversal of 20675721 is 12757602.

It is not a de Polignac number, because 20675721 - 2¹ = 20675719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20675701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6345 + ... + 9033.

It is an arithmetic number, because the mean of its divisors is an integer number (1888380).

Almost surely, 2^20675721 is an apocalyptic number.

It is an amenable number.

20675721 is a deficient number, since it is larger than the sum of its proper divisors (9538359).

20675721 is a wasteful number, since it uses less digits than its factorization.

20675721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2936.

The product of its (nonzero) digits is 5880, while the sum is 30.

The square root of 20675721 is about 4547.0563005092. The cubic root of 20675721 is about 274.4649475316.

The spelling of 20675721 in words is "twenty million, six hundred seventy-five thousand, seven hundred twenty-one".