21251234947 has 2 divisors, whose sum is σ = 21251234948. Its totient is φ = 21251234946.

The previous prime is 21251234891. The next prime is 21251235029. The reversal of 21251234947 is 74943215212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21251234947 - 2¹⁵ = 21251202179 is a prime.

It is a super-2 number, since 2×21251234947² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21251234447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625617473 + 10625617474.

It is an arithmetic number, because the mean of its divisors is an integer number (10625617474).

Almost surely, 2^21251234947 is an apocalyptic number.

21251234947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251234947 is an equidigital number, since it uses as much as digits as its factorization.

21251234947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 40.

The spelling of 21251234947 in words is "twenty-one billion, two hundred fifty-one million, two hundred thirty-four thousand, nine hundred forty-seven".