21515422501091 has 2 divisors, whose sum is σ = 21515422501092. Its totient is φ = 21515422501090.

The previous prime is 21515422501087. The next prime is 21515422501213. The reversal of 21515422501091 is 19010522451512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21515422501091 - 2² = 21515422501087 is a prime.

It is not a weakly prime, because it can be changed into another prime (21515422501891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757711250545 + 10757711250546.

It is an arithmetic number, because the mean of its divisors is an integer number (10757711250546).

Almost surely, 2^{21515422501091} is an apocalyptic number.

21515422501091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515422501091 is an equidigital number, since it uses as much as digits as its factorization.

21515422501091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36000, while the sum is 38.

The spelling of 21515422501091 in words is "twenty-one trillion, five hundred fifteen billion, four hundred twenty-two million, five hundred one thousand, ninety-one".