21076508778 has 32 divisors (see below), whose sum is σ = 48065887296. Its totient is φ = 6103603968.

The previous prime is 21076508759. The next prime is 21076508809. The reversal of 21076508778 is 87780567012.

It is a super-2 number, since 2×21076508778² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a self number, because there is not a number n which added to its sum of digits gives 21076508778.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7946076 + ... + 7948727.

It is an arithmetic number, because the mean of its divisors is an integer number (1502058978).

Almost surely, 2^21076508778 is an apocalyptic number.

21076508778 is an abundant number, since it is smaller than the sum of its proper divisors (26989378518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21076508778 is a wasteful number, since it uses less digits than its factorization.

21076508778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15894838.

The product of its (nonzero) digits is 1317120, while the sum is 51.

The spelling of 21076508778 in words is "twenty-one billion, seventy-six million, five hundred eight thousand, seven hundred seventy-eight".