21941503778 has 4 divisors (see below), whose sum is σ = 32912255670. Its totient is φ = 10970751888.

The previous prime is 21941503769. The next prime is 21941503817. The reversal of 21941503778 is 87730514912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20938958209 + 1002545569 = 144703^2 + 31663^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5485375943 + ... + 5485375946.

Almost surely, 2^21941503778 is an apocalyptic number.

21941503778 is a deficient number, since it is larger than the sum of its proper divisors (10970751892).

21941503778 is a wasteful number, since it uses less digits than its factorization.

21941503778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10970751891.

The product of its (nonzero) digits is 423360, while the sum is 47.

The spelling of 21941503778 in words is "twenty-one billion, nine hundred forty-one million, five hundred three thousand, seven hundred seventy-eight".