21212021947 has 2 divisors, whose sum is σ = 21212021948. Its totient is φ = 21212021946.

The previous prime is 21212021927. The next prime is 21212021959. The reversal of 21212021947 is 74912021212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21212021947 - 2¹⁵ = 21211989179 is a prime.

It is not a weakly prime, because it can be changed into another prime (21212021917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606010973 + 10606010974.

It is an arithmetic number, because the mean of its divisors is an integer number (10606010974).

Almost surely, 2^21212021947 is an apocalyptic number.

21212021947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212021947 is an equidigital number, since it uses as much as digits as its factorization.

21212021947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The spelling of 21212021947 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, nine hundred forty-seven".