21231601 has 2 divisors, whose sum is σ = 21231602. Its totient is φ = 21231600.

The previous prime is 21231583. The next prime is 21231611. The reversal of 21231601 is 10613212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14861025 + 6370576 = 3855^2 + 2524^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231601 - 2⁷ = 21231473 is a prime.

It is not a weakly prime, because it can be changed into another prime (21231611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615800 + 10615801.

It is an arithmetic number, because the mean of its divisors is an integer number (10615801).

Almost surely, 2^21231601 is an apocalyptic number.

It is an amenable number.

21231601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231601 is an equidigital number, since it uses as much as digits as its factorization.

21231601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21231601 is about 4607.7761447362. The cubic root of 21231601 is about 276.9029492276.

Adding to 21231601 its reverse (10613212), we get a palindrome (31844813).

It can be divided in two parts, 212 and 31601, that added together give a palindrome (31813).

The spelling of 21231601 in words is "twenty-one million, two hundred thirty-one thousand, six hundred one".