21990545 has 8 divisors (see below), whose sum is σ = 26464320. Its totient is φ = 17542000.

The previous prime is 21990541. The next prime is 21990557. The reversal of 21990545 is 54509912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21990545 - 2² = 21990541 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21990541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4331 + ... + 7920.

It is an arithmetic number, because the mean of its divisors is an integer number (3308040).

Almost surely, 2^21990545 is an apocalyptic number.

It is an amenable number.

21990545 is a deficient number, since it is larger than the sum of its proper divisors (4473775).

21990545 is a wasteful number, since it uses less digits than its factorization.

21990545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12615.

The product of its (nonzero) digits is 16200, while the sum is 35.

The square root of 21990545 is about 4689.4077451209. The cubic root of 21990545 is about 280.1637859774.

The spelling of 21990545 in words is "twenty-one million, nine hundred ninety thousand, five hundred forty-five".