20991554 has 8 divisors (see below), whose sum is σ = 31511568. Its totient is φ = 10487700.

The previous prime is 20991533. The next prime is 20991577. The reversal of 20991554 is 45519902.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29 + ... + 6479.

It is an arithmetic number, because the mean of its divisors is an integer number (3938946).

Almost surely, 2^20991554 is an apocalyptic number.

20991554 is a deficient number, since it is larger than the sum of its proper divisors (10520014).

20991554 is a wasteful number, since it uses less digits than its factorization.

20991554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8080.

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

The square root of 20991554 is about 4581.6540681287. The cubic root of 20991554 is about 275.8554255774.

The spelling of 20991554 in words is "twenty million, nine hundred ninety-one thousand, five hundred fifty-four".