21748978507 has 2 divisors, whose sum is σ = 21748978508. Its totient is φ = 21748978506.

The previous prime is 21748978487. The next prime is 21748978519. The reversal of 21748978507 is 70587984712.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21748978507 is a prime.

It is not a weakly prime, because it can be changed into another prime (21748988507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10874489253 + 10874489254.

It is an arithmetic number, because the mean of its divisors is an integer number (10874489254).

Almost surely, 2^21748978507 is an apocalyptic number.

21748978507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21748978507 is an equidigital number, since it uses as much as digits as its factorization.

21748978507 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7902720, while the sum is 58.

The spelling of 21748978507 in words is "twenty-one billion, seven hundred forty-eight million, nine hundred seventy-eight thousand, five hundred seven".