20401571 has 2 divisors, whose sum is σ = 20401572. Its totient is φ = 20401570.

The previous prime is 20401561. The next prime is 20401603. The reversal of 20401571 is 17510402.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20401571 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (20401501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200785 + 10200786.

It is an arithmetic number, because the mean of its divisors is an integer number (10200786).

Almost surely, 2^20401571 is an apocalyptic number.

20401571 is a deficient number, since it is larger than the sum of its proper divisors (1).

20401571 is an equidigital number, since it uses as much as digits as its factorization.

20401571 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 20401571 is about 4516.8098255295. The cubic root of 20401571 is about 273.2464554680.

Adding to 20401571 its reverse (17510402), we get a palindrome (37911973).

The spelling of 20401571 in words is "twenty million, four hundred one thousand, five hundred seventy-one".