21461551399 has 2 divisors, whose sum is σ = 21461551400. Its totient is φ = 21461551398.

The previous prime is 21461551381. The next prime is 21461551457. The reversal of 21461551399 is 99315516412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21461551399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21461555399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10730775699 + 10730775700.

It is an arithmetic number, because the mean of its divisors is an integer number (10730775700).

Almost surely, 2^21461551399 is an apocalyptic number.

21461551399 is a deficient number, since it is larger than the sum of its proper divisors (1).

21461551399 is an equidigital number, since it uses as much as digits as its factorization.

21461551399 is an evil number, because the sum of its binary digits is even.

The product of its digits is 291600, while the sum is 46.

The spelling of 21461551399 in words is "twenty-one billion, four hundred sixty-one million, five hundred fifty-one thousand, three hundred ninety-nine".