21499780804 has 12 divisors (see below), whose sum is σ = 37819563964. Its totient is φ = 10694191104.

The previous prime is 21499780801. The next prime is 21499780807. The reversal of 21499780804 is 40808799412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21499780801) and next prime (21499780807).

It can be written as a sum of positive squares in 2 ways, for example, as 7961992900 + 13537787904 = 89230^2 + 116352^2 .

It is not an unprimeable number, because it can be changed into a prime (21499780801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13923957 + ... + 13925500.

Almost surely, 2^21499780804 is an apocalyptic number.

It is an amenable number.

21499780804 is a deficient number, since it is larger than the sum of its proper divisors (16319783160).

21499780804 is a wasteful number, since it uses less digits than its factorization.

21499780804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27849654 (or 27849652 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 21499780804 in words is "twenty-one billion, four hundred ninety-nine million, seven hundred eighty thousand, eight hundred four".