21748978487 has 2 divisors, whose sum is σ = 21748978488. Its totient is φ = 21748978486.

The previous prime is 21748978483. The next prime is 21748978507. The reversal of 21748978487 is 78487984712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21748978487 - 2² = 21748978483 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21748978483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10874489243 + 10874489244.

It is an arithmetic number, because the mean of its divisors is an integer number (10874489244).

Almost surely, 2^21748978487 is an apocalyptic number.

21748978487 is a deficient number, since it is larger than the sum of its proper divisors (1).

21748978487 is an equidigital number, since it uses as much as digits as its factorization.

21748978487 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50577408, while the sum is 65.

The spelling of 21748978487 in words is "twenty-one billion, seven hundred forty-eight million, nine hundred seventy-eight thousand, four hundred eighty-seven".