21403301261 has 2 divisors, whose sum is σ = 21403301262. Its totient is φ = 21403301260.

The previous prime is 21403301221. The next prime is 21403301273. The reversal of 21403301261 is 16210330412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21282433225 + 120868036 = 145885^2 + 10994^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21403301261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21403301221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701650630 + 10701650631.

It is an arithmetic number, because the mean of its divisors is an integer number (10701650631).

Almost surely, 2^21403301261 is an apocalyptic number.

It is an amenable number.

21403301261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403301261 is an equidigital number, since it uses as much as digits as its factorization.

21403301261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

Adding to 21403301261 its reverse (16210330412), we get a palindrome (37613631673).

The spelling of 21403301261 in words is "twenty-one billion, four hundred three million, three hundred one thousand, two hundred sixty-one".