21356150021 has 2 divisors, whose sum is σ = 21356150022. Its totient is φ = 21356150020.

The previous prime is 21356149979. The next prime is 21356150029. The reversal of 21356150021 is 12005165312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13511505121 + 7844644900 = 116239^2 + 88570^2 .

It is a cyclic number.

It is not a de Polignac number, because 21356150021 - 2³⁴ = 4176280837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21356150029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678075010 + 10678075011.

It is an arithmetic number, because the mean of its divisors is an integer number (10678075011).

Almost surely, 2^21356150021 is an apocalyptic number.

It is an amenable number.

21356150021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356150021 is an equidigital number, since it uses as much as digits as its factorization.

21356150021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 26.

The spelling of 21356150021 in words is "twenty-one billion, three hundred fifty-six million, one hundred fifty thousand, twenty-one".