20723551 has 6 divisors (see below), whose sum is σ = 21024656. Its totient is φ = 20426700.

The previous prime is 20723543. The next prime is 20723557. The reversal of 20723551 is 15532702.

It is not a de Polignac number, because 20723551 - 2³ = 20723543 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20723557) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2986 + ... + 7096.

Almost surely, 2^20723551 is an apocalyptic number.

20723551 is a deficient number, since it is larger than the sum of its proper divisors (301105).

20723551 is an frugal number, since it uses more digits than its factorization.

20723551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4253 (or 4182 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 20723551 is about 4552.3127089426. The cubic root of 20723551 is about 274.6764282423.

The spelling of 20723551 in words is "twenty million, seven hundred twenty-three thousand, five hundred fifty-one".