21502121401 has 2 divisors, whose sum is σ = 21502121402. Its totient is φ = 21502121400.

The previous prime is 21502121393. The next prime is 21502121411. The reversal of 21502121401 is 10412120512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18285530176 + 3216591225 = 135224^2 + 56715^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502121401 - 2³ = 21502121393 is a prime.

It is a super-3 number, since 3×21502121401³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21502121411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10751060700 + 10751060701.

It is an arithmetic number, because the mean of its divisors is an integer number (10751060701).

Almost surely, 2^21502121401 is an apocalyptic number.

It is an amenable number.

21502121401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21502121401 is an equidigital number, since it uses as much as digits as its factorization.

21502121401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 19.

Adding to 21502121401 its reverse (10412120512), we get a palindrome (31914241913).

The spelling of 21502121401 in words is "twenty-one billion, five hundred two million, one hundred twenty-one thousand, four hundred one".